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The Lebranche mullet Mugil liza is a marine fish of great importance for artisanal and industrial fishing, as well as aquaculture. The use of live feeds during the larviculture phase of marine fish is a significant component of production costs. The present study evaluated the effects of the feeding transition on different larval stages of M. liza, from the combined supply of live feed (Brachionus rotundiformis + Artemia franciscana) and live + inert feed (Artemia franciscana + inert diet) until the weaning phase to only the inert diet. A total of 3240 M. liza larvae (weight 0.0133 ± 0.0062 g and length 0.793 ± 0.160 cm) were distributed among the 12 experimental units (n = 270), resulting in four groups with three replicates each. Treatment groups consisted of feed transition with A. franciscana (enriched metanauplii) to commercial inert feed starting weaning at four different larval ages: 28, 31, 34, and 37 days post hatching. Zootechnical performance indexes and intestinal histomorphometry were evaluated. Mortality, condition factor, and length variation coefficient did not show significant differences between treatments. Final weight, final length, weight gain, and length gain were significantly greater in larvae that started weaning at 31, 34, and 37 days post hatching. Weight coefficient of variation was significantly higher in larvae that started weaning at 28 days (67.51 ± 11.70) compared to 37 days (34.40 ± 7.30). In intestinal histology, villi height (180.3 ± 4.4) was significantly higher in larvae that started weaning at 37 days post hatching. Considering the evidence found in the present study, it is recommended to start weaning M. liza on the 31st day post‐hatching, using a 2‐day co‐feeding protocol (31st and 32nd days). From the 33rd day after hatching, M. liza larvae can receive only commercial feed. [ABSTRACT FROM AUTHOR]

One of the most persistent challenges in walleye larviculture is the high rate of unobserved mortality occurring within the first 30 days post-hatch. Walleye larviculture is characterized by high mortality rates, but oftentimes, only a fraction of the total mortality in walleye larviculture is observed. Unobserved mortality is frequently attributed to a high rate of cannibalism, but decomposition of larvae and other factors may also be important contributors. Unobserved mortality can make walleye larviculture especially challenging as accurately estimating daily feed rations and forecasting larval production rely on accurate counts of surviving fish. Despite the importance of unobserved mortality, there is little empirical evidence available that assesses the temporal occurrence and causes of unobserved mortality in walleye larviculture. This study assessed when unobserved mortality occurs during walleye larviculture by examining survival at three timepoints (8, 15, and 30 days post-stocking). Tanks were cleaned daily and dead fry were enumerated to account for observed mortality. At the end of each treatment period, the tanks were drained, all remaining fry were enumerated, and the unobserved mortality rate was calculated. While observed mortality trended higher as trial duration increased, unobserved mortality did not increase significantly from the 8-day treatment suggesting that the bulk of unobserved mortality occurs during the first 8 days of walleye larviculture. [ABSTRACT FROM AUTHOR]

ABSTRACT This study evaluated the effect of co-feeding with commercial feed and live food (enriched or not with microalgae) on the growth and survival of Trachelyopterus galeatus larvae. Five treatments were carried out: commercial feed as a control (F); brine shrimp nauplii (BS); brine shrimp nauplii enriched with Chaetoceros sp. Microalgae (BSM); combined feed with brine shrimp nauplii (F+BS) and combined feed with brine shrimp nauplii enriched with microalgae (FBSM). The larvae (5.00±0.02 mg and 5.95±0.33mm) were reared for 30 days. There were no significant differences (P>0.05) in water quality between treatments, but there were significant differences in weight, weight gain and survival. The F+BS and F+BSM treatments, which involved co-feeding, showed the best results in final weight (0.168±0.004g and 0.169±0.007g) and weight gain (0.1278±0.004 g and 0.1294±0.007g), respectively. The treatments with live food, enriched or not, showed high survival rates of over 73%, with no significant differences between them. On the other hand, the exclusive use of feed resulted in low survival (36.7 ± 9.53%), indicating that this may result in low growth and make the production of T. galeatus larvae unfeasible.

Aquaculture plays a crucial role in meeting the increasing global demand for food and protein sources. However, its expansion is followed by increasing challenges, such as infectious disease outbreaks and antibiotic misuse. The present study focuses on the genetic and functional analyses of two Lacticaseibacillus paracasei (BF3 and RT4) and two Lactiplantibacillus plantarum (BF12 and WT12) strains isolated from a rotifer cultivation tank used for turbot larviculture. Whole-genome sequencing (WGS) and bioinformatics analyses confirmed their probiotic potential, the absence of transferable antibiotic resistance genes, and the absence of virulence and pathogenicity factors. Bacteriocin mining identified a gene cluster encoding six plantaricins, suggesting their role in the antimicrobial activity exerted by these strains. In vitro cell-free protein synthesis (IV-CFPS) analyses was used to evaluate the expression of the plantaricin genes. The in vitro-synthesized class IIb (two-peptide bacteriocins) plantaricin E/F (PlnE/F) exerted antimicrobial activity against three indicator microorganisms, including the well-known ichthyopathogen Lactococcus garvieae. Furthermore, MALDI-TOF MS on colonies detected the presence of a major peptide that matches the dimeric form of plantaricins E (PlnE) and F (PlnF). This study emphasizes the importance of genome sequencing and bioinformatic analysis for evaluating aquaculture probiotic candidates. Moreover, it provides valuable insights into their genetic features and antimicrobial mechanisms, paving the way for their application as probiotics in larviculture, which is a major bottleneck in aquaculture. [ABSTRACT FROM AUTHOR]

One of the most persistent challenges in walleye larviculture is the high rate of unobserved mortality occurring within the first 30 days post-hatch. Walleye larviculture is characterized by high mortality rates, but oftentimes, only a fraction of the total mortality in walleye larviculture is observed. Unobserved mortality is frequently attributed to a high rate of cannibalism, but decomposition of larvae and other factors may also be important contributors. Unobserved mortality can make walleye larviculture especially challenging as accurately estimating daily feed rations and forecasting larval production rely on accurate counts of surviving fish. Despite the importance of unobserved mortality, there is little empirical evidence available that assesses the temporal occurrence and causes of unobserved mortality in walleye larviculture. This study assessed when unobserved mortality occurs during walleye larviculture by examining survival at three timepoints (8, 15, and 30 days post-stocking). Tanks were cleaned daily and dead fry were enumerated to account for observed mortality. At the end of each treatment period, the tanks were drained, all remaining fry were enumerated, and the unobserved mortality rate was calculated. While observed mortality trended higher as trial duration increased, unobserved mortality did not increase significantly from the 8-day treatment suggesting that the bulk of unobserved mortality occurs during the first 8 days of walleye larviculture.

Context: Balistes capriscus is relevant for fishing worldwide, but there is no consistent information on the maintenance of the species in a captive environment. Aims: Develop protocols for the reproduction of the species in aquaculture systems, contributing to the maintenance of the supply in the commerce through captive breeding. Methods: A Balistes capriscus couple was selected on the basis of behavioural observations. Nutritional and environmental stimuli were invested in obtaining natural spawning. After reproduction, the larvae were regularly observed under an microscope to monitor the ontogenic development. In larviculture, feeds based on Brachionus plicatilis (10 mL−1) and Nannochloropsis oculata (150 000 cells mL−1) and pate formulated with Artemia salina , Nannochloropsis oculata , sardines and commercial feed were evaluated. Key results: The eggs had a diameter of 667.5 μm (±21.66) and formed a mass adhered to the substrate. Newly hatched larvae had a total length of 1653.63 μm (±213.97). The first food intake was evidenced 72 h after hatching; however, larvae did not survive more than 6 days. Conclusions: The reproduction in laboratory of the species is viable; however, larviculture remains a limiting factor. Implications: The success in captive breeding is essential for the introduction of B. capriscus in aquaculture, and for the conservation of the species. This study observed the formation of a pair within a group of grey triggerfish (Balistes capriscus) in the laboratory, culminating in reproduction and enabling studies on the larviculture of the species. The results indicated that it is possible to keep small groups of breeders in captivity, but the individualisation of couples may be necessary, because of the aggressiveness towards other individuals. The hatchery phase is still a strong limiting factor for the artificial propagation of the species, because it demonstrates specificity regarding the first exogenous food. [ABSTRACT FROM AUTHOR]

Summary: Brazilian basslet Gramma brasiliensis is a fish highly appreciated by the marine ornamental industry. There is an increasing interest in the development of a breeding protocol for this species. However, descriptions of the reproductive biology, eggs and larval development are scarce. This study was the first to describe the spawning, eggs and larvae of G. brasiliensis in captivity, including mouth size information. Six spawning events produced egg masses with 27, 127, 600, 750, 850, and 950 eggs. Larger egg masses showed embryos with at least two different developmental stages. Eggs are spherical (∼1.0 mm diameter), held together by filaments entangling chorionic projections. Larvae with fewer than 12 hph (hours post-hatch) presented 3.55 mm standard-length, well developed eyes, fully absorbed yolk sac, an inflated swim bladder and mouth opened. Exogenous feeding on rotifers began within 12 hph. The average mouth width at first feeding was 0.38 mm. The first settled larva was noted by day 21. This information should help to determine appropriate diets and prey-shift time during the larviculture of the species. [ABSTRACT FROM AUTHOR]

Simple Summary: High flesh quality, along with a good potential for intensive farming in a Recirculating Aquaculture System (RAS), make the pike-perch (Sander lucioperca) a valuable fish species both from the industry and the research point of view. Although high electricity demands have been attributed to it, fish farming in a RAS is recognized as the key strategy for sustainable fish farming, given its minimal usage of natural resources as well as its independence of outdoor weather conditions. Although the older juvenile stages of pike-perch are well adapted to indoor rearing conditions, the larval and early juvenile stages seem to be particularly sensitive to indoor rearing. Switching to the indoor production of pike-perch larvae would support the continuous, weather-independent, production of fish throughout the year. Hence, our study aimed to identify the pros and cons of rearing pike-perch larvae and early juveniles (nursing period) in indoor versus outdoor systems. For this purpose, we compared the effects of pike-perch nursing in both systems on the later growth and survival of the fish. Our results show that, although nursing indoors increases fish mortality, it provides a basis for improved fish growth later in life. This can eventually shorten the period for the production of market-size fish, and, along with the advantages related to the year-round production of larvae, provide higher yields to fish farmers in the long run. This study aimed to estimate the efficacy of two pike-perch juvenile production technologies: exclusive Recirculating Aquaculture System (RAS) culture (the RAS group) and pond larviculture with a transfer to the RAS at the 42nd day post-hatch (DPH). Both direct weaning on dry feed (the Pond-D group) and 10-day gradual weaning using bloodworms (the Pond-B group) after transfer to the RAS were evaluated in pond-nursed fry. Their survival and morphometric indices were monitored after the RAS habituation period (first 10 days), after the 18-day post-habituation period and after an additional 30 days of on-grow. Our results indicate a negative allometric growth of the pond-nursed fish during the nursing period, which was slower (p < 0.0001) in comparison to the RAS-nursed fry (16.3 ± 0.4 vs. 17.8 ± 0.7%/day). After transfer, these fish grew faster than the RAS-nursed fry (7.7 ± 0.1, 4.9 ± 0.5 and 6.1 ± 0.6 during habituation, 8.5 ± 0.6, 9.3 ± 0.5 and 6.7 ± 0.1%/day during post-habituation period, in the Pond-B, Pond-D and RAS groups, respectively). However, four weeks afterwards, the RAS-nursed fry were again superior in terms of growth (4.0 ± 0.1, 3.6 ± 0.2 and 4.6 ± 0.2%/day, for the Pond-B, Pond-D and RAS groups, respectively), and this was accompanied by a significantly lower feed conversion ratio in this group. Although the survival of the RAS-nursed fry during the nursing period was lower in comparison to the pond-reared fry (11.3 vs. 67.3%), the RAS seems to provide a long-term growth advantage. [ABSTRACT FROM AUTHOR]

Larval mortality constitutes the major bottleneck in Centropyge species aquaculture. Marine fish eggs and larvae are sensitive to abiotic conditions variations, as salinity. Captive natural spawning of Centropyge aurantonotus were used to evaluate effects of salinity on eggs and larvae up to 72 hours post hatch (hph). Eggs were transferred from 33‰ to 10‰, 15‰, 20‰, 25‰, 30‰, 35‰ and 40‰ salinity, 27 ± 0.2°C. Buoyancy, water column distribution, incubation period and hatching rate were evaluated in eggs. For larvae, swimming behaviour, water column distribution, survival rates, standard length, yolk sac and oil drop volume, conversion rate of yolk sac in growth, pigmentation, deformities, mouth size and eye diameter were examined. The buoyancy was positive at salinities >30‰, positive to neutral at 30‰ and negative at <30‰. Neutrally buoyant eggs and larvae showed greater water column distribution than positive and negatively buoyant ones. Swimming behaviour was active in positive and neutral buoyancy. Incubation period was inversely proportional to salinity increase. Hatching rate was higher at 30‰, when compared to 10‰ and 15‰. At 10‰–25‰, deformities and high mortality rates of larvae were observed. Between 30‰ and 40‰, larvae of 72 hph showed no deformities, active swimming behaviour, higher survival rate (~87%), greater mouth size (~129.81 μm) and eye diameter (~170.1 μm) than 10‰ and 15‰. Salinities between 30‰ and 40‰ were adequate for rearing C. aurantonotus eggs and larvae up to 72 hph, 30‰ salinity increased their water column distribution and optimized hatching rate and adverse effects occurs at 10‰–25‰. [ABSTRACT FROM AUTHOR]

Microalgae are essential for most aquaculture hatcheries as first‐feed for larvae. Even so, high labour costs and risk of production crashes have encouraged the search for fresh culture substitutes, such as microalgae concentrates. Despite their importance as a commodity for the aquaculture sector, the concentrates are not available worldwide, and consolidated knowledge is scarce. Therefore, this bibliographic study aimed review microalgae products available for hatcheries, identifying research gaps and suggesting opportunities for development. In most studies, microalgae cultures were harvested by centrifugation, and biomass was stored chilled, frozen or dried (heat‐, spray‐ or freeze‐dried). The shelf life of microalgae products was dependent on the method of storage and microalgae species since robust species maintained their nutritional value for a longer period compared to more fragile ones, which would be sensitive to harvesting and storage. Thus, the use of concentrates in some feeding trials resulted in poor zootechnical performance. These results have four possible explanations: cell ingestion difficulty, low feed digestibility by phytoplanktivores animals, biomass degradation or inadequate choice of microalgae species. However, these limitations can be overcome by fractionating feed portions and adapting the culture tanks and aeration systems, but mainly by determining the ideal method for storing biomass and shelf life for each microalgae species. Taken together, our findings show that the application of microalgae concentrates can enhance the efficiency and profitability of aquaculture hatcheries. [ABSTRACT FROM AUTHOR]

Increasing the number of fish stocked might optimize the efficiency of intensive aquaculture systems however at the same time might have a negative impact on fish welfare and growth parameters. In the current study, three different stocking densities were evaluated in duplicated tanks to investigate the effect of different stocking densities on the survival and growth of sterlet larvae from hatching until the end of weaning, during the 30‐day trial. Tested densities were 5, 10, and 20 larvae L−1 in the low (L), medium (M), and high (H) density group, respectively. Freshly hatched larvae (1250, 2500, 5000 larvae per duplicated tanks) were divided into three treatment groups in 250 L raceway larval rearing tanks. The fish biomass gain was significantly higher in each group of higher stocking densities (0.2 ± 0.0 g L−1; 0.4 ± 0.0 g L−1 and 0.8 ± 0.1 g L−1 respectively, r =.990, p <.001). The L group showed a tendency towards better growth during the first 3 weeks, however, at the end of the trial, no significant differences were observed. The highest mortality at the start of exogenous feeding was noticed in group H (12.77% ± 1.3%) and was significantly different from the two lower density groups (5.16% ± 1.3% in L, 7.94% ± 1.3% in M), however, the overall mortality at the end of the trial did not differ among groups. Results on both growth and mortality during the later periods are suggesting the adaptability of sterlet larvae to the more intensive rearing conditions. Thus, it can be stated that the application of a stocking density of 20 larvae L−1 is appropriate in the initial period of larval rearing in the sterlet. [ABSTRACT FROM AUTHOR]

Intensive aquaculture food production has been continually increasing over the past decades. Recirculating aquaculture is an innovative technology which relies on water reuse and removal of toxic metabolites by utilizing specific prokaryotic groups such as nitrifiers, settled in special biofilters. Focused on recent next generation sequencing‐based studies on the microbiome of recirculating aquaculture systems, this review highlights dominant genera and families, and investigates their possible metabolic function in key niches within recirculating aquaculture systems (rearing water, biofilters and fish mucosal microbiome), while aiming to identify core prokaryotic groups across studies. A total of 136 genera belonging to 77 families and 13 phyla have been characterized as dominant or functionally important in relevant studies, mainly isolated from nitrification biofilters, system water and intestinal samples of the farmed species. Proteobacteria is undoubtedly the most abundant phylum, followed by Bacteroidetes, Firmicutes and Actinobacteria, while Rhodobacteriaceae and Flavobacteriaceae are the common dominant families. Nitrosomonadaceae and Nitrospira members are enriched in biofilter samples and serve as the most common ammonium and nitrite oxidizers, respectively. Composition of dominant genera appears system specific due to unique characteristics of individual RAS designs, although faint community patterns emerge when examining RAS by their salinity level. Considering the number of ribosomal RNA operon copies, 75% of genera are likely slow growers, dominating biofilter and water communities, whereas the few fast‐growing opportunists are mainly associated with the intestine of farmed species. Finally, this review stresses the lack of information regarding archaeal and microeukaryotic communities in recirculating aquaculture systems and prokaryotic–protist interactions. [ABSTRACT FROM AUTHOR]

The present study evaluated the effect of initial stocking density and water recirculation rate on larval yield (percent of initially stocked larvae alive at the end of the experiment) and production of competent larvae (percent of initially stocked larvae alive at the end of the experiment retained on a sieve with mesh size 239 μm) of Crassostrea gigas in a recirculation aquaculture system (RAS). Different initial larval stocking densities (80, 160 and 320 larvae mL−1) and water flow rates (100, 200 and 300 mL min−1, totalling renewal rates of 60, 120 and 180 times day−1 of water volume in culture tanks, respectively) were evaluated in 2.4-L tanks using a completely randomized design in a factorial scheme. The physicochemical parameters of the water (temperature, salinity, pH, dissolved oxygen and conductivity) were stable in all treatments during the experimental period. Our results demonstrated that the production of C. gigas larvae was feasible at the proposed densities. However, the water renewal rate affected both yield and competent larvae in the recirculation aquaculture system. Oyster cultures with densities of 160 larvae mL−1 and flow of water of 300 mL min−1 showed the best yield (89.34 ± 18.43%) and rate of competent larvae (84.09 ± 16.38%) and are therefore recommended with the aim of optimizing larvae cultivation. [ABSTRACT FROM AUTHOR]

Four-day-old hybrid striped bass (HSB; Morone chrysops x M. saxatilis) larvae were stocked into a recirculating aquaculture system maintained at 18°C to mimic cool-water culture temperatures experienced by year-round producers to determine the earliest time HSB larvae could be weaned from Artemia to a commercial diet. After an initial 8-day rotifer feeding period where all treatments were fed three times daily with rotifers (60 rotifers/mL/tank/d), designated replicated treatments were progressively weaned from Artemia (12 Artemia/mL/tank/d) onto starter (3.0 g/tank/d) for 8 to 28 days in 4-day increments (DFA) for a total of six treatments. Survival of larvae by the end of the experiment ranged from 12.9% to 64.1% and averaged 31.2 ± 12.6% with no significant difference among treatments. At the end of the study, length of larvae ranged from 9.05 to 19.06 mm (mean 14.19 ± 1.92 mm), and body depth of larvae ranged from 1.52 to 4.35 mm (mean 2.71 ± 0.56 mm). Total length and body depth of larvae varied significantly based on DFA (P < 0.0001), with the largest larvae being the ones fed Artemia for the longest. Refinements of these feeding methods will help farmers more easily transition to tank-based production schemes, lead to year-round availability of fingerlings, and aid in expansion of the HSB aquaculture industry. [ABSTRACT FROM AUTHOR]

Barramundi, the Asian sea bass (Lates calcarifer Bloch 1790), is a valuable aquaculture commodity, but seed survival is generally low. This study used a completely randomized design (two factors; 16 treatments; 3 replicates) to examine the effect of adding vitamin B complex and phosphorus to the rearing media on the survival, stress resistance, and phosphorus content of barramundi larvae. Barramundi larvae aged two days were stocked at a density of 25 fish L-1 in 40 L green plastic basins (30 L water) and reared for 30 days with natural feed (Chlorella and rotifers). The factor I was vitamin B complex with 4 levels: 0, 75, 150, and 225 mg L-1. Factor II was phosphorus with four levels: 0, 0.5, 1.0, and 1.5 mg L-1. Commercially available B vitamin complex and phosphorus mineral supplements were dissolved in water and added to the larval-rearing media. Analysis of variance showed that the combination of vitamin B complex and phosphorus treatments had a significant effect (P < 0.01) on survival, stress resistance, and phosphorus uptake. Survival and phosphorus content in barramundi larvae were highest with a combination of 150 mg L-1 vitamin B complex and 1.0 mg L-1 phosphorus and lowest in control (0 mg L-1 of both additives). [ABSTRACT FROM AUTHOR]

Sea cucumber Holothuria nobilis is an economically important species for livelihoods in many countries. However, an increase in demand for this species has led to the depletion of wild stocks. The introduction of this species in aquaculture is necessary to reduce fishing pressure. This study was taken to establish breeding and larval rearing techniques for the development of H. nobilis aquaculture. The broodstock collected from the wild were induced to spawn by using thermal stimulation and the combination of thermal and algal stimulation methods. The larvae obtained from induced spawning were reared using different diets (mixed microalgae and mixed microalgae with artificial feeds) at different stocking densities (300, 600, and 1000 larvae/l). Thermal stimulation is the best method of inducing spawning to H. nobilis yielding up to 1,300,000 fertilized eggs. The highest survival rate (27.5%) of doliolaria larvae was achieved using a mixed microalgae diet. The highest survival rate of doliolaria larvae (41.5 %), growth, and development were in the stocking density of 600 larvae/ [ABSTRACT FROM AUTHOR]

ABSTRACT: Anomalocardia brasiliana post-larvae were cultured for 28 days to evaluate the effect of stocking density on their growth and survival rate. Three stocking densities were tested 40, 80 and 160 post-larvae cm-2, in experimental units (2-L) with static cultivation system and total water renewal at each 48 hours. The experimental design was completely randomized with three treatments and three repetitions each. Stocking density of 40 post-larvae cm-2 reached 1 mm length within 24 days, while only 18% of the post-larvae at density of 80 post-larvae cm-2 reached 1 mm length in the same time. The density of 40 post-larvae cm-2 had the highest specific growth rate, 4.98±0.08% day-1. The survival rates of post-larvae at lower densities were significantly higher (53.24±4.60% and 52.95±3.32%, on 40 and 80 post-larvae cm-2, respectively) compared to higher stocking density (31.54±0.70%). In the cultivation of A. brasiliana post-larvae, stocking density must be managed during growth. The density of 160 post-larvae cm-2 can only be used until the post-larvae reach 600μm in length, then they should be at 40 post-larvae cm-2 density to keep the maximum daily growth rate.

Anomalocardia brasiliana post-larvae were cultured for 28 days to evaluate the effect of stocking density on their growth and survival rate. Three stocking densities were tested 40, 80 and 160 post-larvae cm-2, in experimental units (2-L) with static cultivation system and total water renewal at each 48 hours. The experimental design was completely randomized with three treatments and three repetitions each. Stocking density of 40 post-larvae cm-2 reached 1 mm length within 24 days, while only 18% of the post-larvae at density of 80 postlarvae cm-2 reached 1 mm length in the same time. The density of 40 post-larvae cm-2 had the highest specific growth rate, 4.98±0.08% day-1. The survival rates of post-larvae at lower densities were significantly higher (53.24±4.60% and 52.95±3.32%, on 40 and 80 post-larvae cm-2, respectively) compared to higher stocking density (31.54±0.70%). In the cultivation of A. brasiliana post-larvae, stocking density must be managed during growth. The density of 160 post-larvae cm-2 can only be used until the post-larvae reach 600µm in length, then they should be at 40 post-larvae cm-2 density to keep the maximum daily growth rate. [ABSTRACT FROM AUTHOR]

The European brown shrimp, Crangon crangon, is a highly valued commercial species in Europe. These shrimp fisheries are characterized by strong seasonal variations in average landings. Attempts to 'catch and hold' wild adults in land‐based rearing systems have been proven to be very difficult, due to inadequate feed, slow growth and high mortality. In this study, we have optimized design and operation procedures of a small‐scale static larval rearing system for the culture of C. crangon larvae. Focus was on optimizing larval survival via water temperature, feed selection, feeding regime and density. This is the first report that shows that C. crangon larvae can be reared at high densities of 300 larvae L‐1 with high survival of 73.5 (± 5.4)% under laboratory conditions. In these systems, larvae can be fed exclusively Artemia nauplii according to a feeding regime which is adjusted based on major moulting events. Addition of microalgae may further increase survival by 10%. The information gathered during this research can be applied to further optimize larval development in either flow‐through or recirculation systems. [ABSTRACT FROM AUTHOR]

The barber goby Elacatinus figaro is an endangered fish, endemic to Brazil and very important to the aquarium trade. One of the bottlenecks for its production in captivity is the larviculture, which is characterized by high mortality rates, especially in the first week after hatching, and prior to metamorphosis. The experiment evaluated the effect of triiodothyronine hormone (T3) on survival, growth and metamorphosis of barber goby. Larvae of 14 days after hatching (DAH) were immersed in three concentrations of T3, in triplicate: TC (control) – 0; T01 – 0.01; T025 – 0.025 and T05 – 0.05 mg/L. An additional replicate of each treatment was performed for sampling for the histological analysis of the thyroid follicles in 24 DAH larvae. The survival rates in TC, T01, T025 and T05 were 24%, 54%, 36% and 37% respectively, without significant differences between the treatments (p > 0.05). Regarding larval growth, the highest length values were obtained in TC. In T025 and T05, larval metamorphosis was anticipated in up to 11 days in relation to TC and T01. In T01 larvae, follicles were numerous with the presence of reabsorption vesicles in the colloid periphery, indicating increased production of thyroid hormones (THs), associated with the larval metamorphosis process. In T05, a follicle reduction in number and size was observed, given evidence of the end of metamorphosis. The use of 0.025 and 0.05 mg/L of T3 anticipated metamorphosis in barber goby larvae, shortening the larviculture period for this species. [ABSTRACT FROM AUTHOR]

ABSTRACT We assessed the survival of paralarvae kept in a floating wooden box attached to an oyster extensive cultivation system with no extra food supply. A total of 7700 newly hatched paralarvae were maintained in a 10.5-L floating box (7 cm height × 30 cm width × 50 cm length) covered with a 180-μm mesh net for 14 days with no extra food supply. Skin damages and tentacle deformities were observed in 43% of the paralarvae at 14 days after hatching (DAH). The survival rate was 64.7% at 7 DAH and 42.8% at 14 DAH. The floating box is a promising structure for culturing O. vulgaris paralarvae in an extensive system.

Abstract: Temperature and light are important factors affecting production in the aquaculture industry, as they can drive behaviour and physiological responses of free‐swimming larval stages. However, the influence of light on crustacean farming has received little consideration. The common spider crab Maja brachydactyla Balss, 1922 has a great potential for aquaculture because of the easy maintenance, high fecundity, and short larval development. In order to optimize larval culture techniques, we quantified the influence of temperature and light on larval survival, development, and elemental (carbon and nitrogen) body composition. Constant darkness resulted in longer developmental time as compared with daily light photoperiod (6–16 light hours). Larvae reared under constant darkness showed also reduced dry mass, carbon and nitrogen content, and C:N ratio. We also found carry‐over effects of light conditions: constant darkness experienced during the zoeal stage led to increased developmental time in the megalopa stage. Temperature and light showed additive effects. We optimized the larval culture of M. brachydactyla requiring around 14 days from hatch to first juvenile by keeping cultures under 21 ± 1°C and light sources simulating the daily light cycle. [ABSTRACT FROM AUTHOR]

Abstract: This 28‐day study investigated the effect of three rearing temperatures, 11, 15 and 19°C, on survival and growth of maraena whitefish fry in a recirculating aquaculture system. Three groups of larvae in three repetitions were reared in recirculating system. Each group comprised 200 larvae. Feeding level was fixed at 500–700 Artemia sp. metanauplii per fish per day. Larvae were fed fresh live brine shrimp at 10 ml/tank every 3 hr. Significantly higher body weight (p = 0.00), total length (p = 0.00), larval yield (p = 0.00) and condition factor (p = 0.00) were obtained at 19°C compared to 15 and 11°C, as well as at 15°C compared to 11°C. Significantly higher survival (p = 0.00) was observed in larvae reared at 11 and 15°C compare to 19°C and no significant differences were observed between 11°C compared to 15°C. No significant differences in size heterogeneity among treatments were found (p = 0.46). In larviculture, the optimal assessed temperature for growth of maraena whitefish was 19°C, with highest survival observed at 11°C, at the end of this 28 days trial. The findings in this study apply to the particular study location and may not be applicable more broadly. [ABSTRACT FROM AUTHOR]

Abstract: Astaxanthin is a red secondary carotenoid and powerful antioxidant that is used in aquaculture to enhance colour and improve fish health. Brachionid rotifers are often used as a live feed for larval fish, but do not contain endogenous carotenoids. However, they can be enriched with astaxanthin through their diet and transfer it to larval predators. When supplemented with 2 μg/ml astaxanthin oleoresin extracted from the green alga Haematococcus pluvialis, Brachionus manjavacas rotifer cultures reached significantly higher population densities and maintained them for longer. Furthermore, data are presented that exposure to oleoresin or pure astaxanthin enhances rotifer resistance to oxidative stress, a common cause for the collapse of rotifer mass cultures. Astaxanthin can be visualized in the gut of the rotifers, allowing the time course of uptake to be estimated by image analysis. Using this method, it was found that accumulation of astaxanthin in the rotifer gut saturates after 1.5 hr of exposure. The bioactive dose of astaxanthin oleoresin for rotifers was found to be 1–20 μg/ml. Astaxanthin concentration in rotifer tissues was measured using absorbance spectrophotometry. It was found that treating rotifers with 20 μg/ml for 24 hr; the concentration of astaxanthin absorbed into rotifer tissues was 2.6 mg/g. Overall, these experiments indicate that astaxanthin extracted from H. pluvialis can be used to improve the productivity and stability of rotifer mass cultures by increasing oxidative stress resistance and enhance the nutritional content of rotifers for larval fish. [ABSTRACT FROM AUTHOR]

Sea urchin larvae have developed metamorphosis and settlement stages as an adaptation serving to increase their distribution and find more suitable habitats; for aquaculture farmers, these stages represent a bottleneck, as the cost-effective production of large numbers of metamorphosed larvae in confined conditions remains a major constraint. The aim of this study was the development of a reliable metamorphosis cue for Paracentrotus lividus larvae that is widely available and easy to prepare and use even at the hatchery scale. For this purpose, substrates of environmental origin (GUS - ground Ulva spp. solution) and chemical origin (histamine) were tested for their effectiveness, evaluating the metamorphosis rates of competent P. lividus larvae after 24-h exposure. In addition, differences in metamorphosis rates following exposure to scaled concentrations of both fresh and frozen-thawed GUS were evaluated, with a view to the latter's routine adoption as a metamorphic cue. The metamorphosis rates obtained in the presence of GUS were always around 80%, using both fresh and thawed solutions. Decreasing GUS concentrations resulted in significantly lower percentages of metamorphosed larvae. No metamorphosis occurred after exposure to histamine solutions. GUS proved to be an effective metamorphic cue and to have several other strengths. Indeed, Ulva spp. are widely available and easy to collect in the field as well as being currently cultivated, in some cases in integrated multi-trophic systems. Ulva spp. represent a common food source for natural populations of juvenile and adult P. lividus , and GUS can therefore be used in the formulation of a settlement substrate that also serves as food in the initial post-metamorphosis period. Finally, GUS is prepared by grinding fragments of Ulva spp. with FSW in a mortar and then filtering the solution, with no need for time-consuming or expensive methods. It can thus be easily produced on a commercial scale and then stored or delivered after being frozen. In conclusion, the formulation of GUS represents a promising advance in the development of protocols for echiniculture, meeting the need for tailored metamorphosis and settlement methods that support successful and cost-effective production of sea urchin juveniles. Moreover, it could represent an additional valuable method for obtaining marketable products from harvested Ulva grown in integrated multi-trophic aquaculture systems. [ABSTRACT FROM AUTHOR]

The inexistence of nutritionally adequate diets in paralarval rearing is the main bottleneck for commercial production of the common octopus Octopus cf. vulgaris. We report the feeding behavior of O. vulgaris Type II paralarvae fed on Artemia sp (0.1 individual. mL-1) nauplii enriched with microalgae Isocrysis galbana and Pavlova lutheri microalgae from 0 to 7 Day After Hatching (DAH).; metanauplii enriched with microalgae and DHA SELCO® lipid emulsion from the 8 DAH. The paralarvae showed active swimming and predation by the 14 DAH, feeding in the most superficial portion of the water column. From the 15 DAH, the paralarvae remained near the bottom and there a decrease in the consumption of artemia was observed. The mortality observed from the 18 DAH and mass mortality of paralarvae on 20 DAH can be attributed mainly to the nutritional composition of the diet. Studies analyzing the biochemical composition and ontogeny of the digestive system during the early life stages should shed some light on the running for an appropriate feeding protocol to the paralarval rearing. [ABSTRACT FROM AUTHOR]

In this study, the aim was to establish a protocol for first feeding of diploid and triploid yellowtail tetra Astyanax altiparanae in laboratory conditions. The fry were fed with five different diets: (i) Artemia franciscana nauplii, (ii) plankton, (iii) dry food, (iv) Artemia franciscana nauplii + plankton, and (v) Artemia nauplii + plankton + dry food. Additionally, the growth and survival rates of diploid and triploid individuals were also evaluated. On day 10, the length of the fish between the treatments differed significantly ( p = .0001) and ranged from 4.07 ± 0.06 mm (dry food) to 8.50 ± 0.64 mm (plankton + Artemia). The sizes of the fish increased with time, except for the fish fed with dry food. The survival rates were similar for the fish fed with the four diets and ranged from 80.7 ± 5.4% (dry food + plankton + Artemia to 92.0 ± 1.6% (plankton + Artemia), but differed from the fish fed with dry food (17.7 ± 5.8%, p = .0017). Diploids and triploids did not present differences on day 0 ( p = .2252) and on day 10 ( p = .4844) when the fish presented 6.77 ± 0.25 mm and 6.54 ± 0.15 mm respectively. Survival of diploids (87.3 ± 5.13%) and triploids (74.67 ± 2.30%) were also similar ( p = .0285). These data are innovative and useful for establishing protocols for this species in both academic and applied sciences. [ABSTRACT FROM AUTHOR]

We investigated the effects of body size on the reproductive potential of the males of the Japanese spiny lobster Panulirus japonicus (von Siebold, 1824) under laboratory conditions to develop broodstock management techniques. The males were divided into three groups based on body size, each with three individuals: large (~90 mm carapace length (CL)), medium (~70 mm CL), and small (~60 mm CL). To evaluate the male reproductive potential, male lobsters were individually stocked in compartments in the tanks, and ten females with similar body size (~54-60 mm CL) were assigned to each male. Oviposition, egg fertilization rate, and clutch size were examined for females. Male body size affected the rates of oviposition and egg fertilization of the partners, resulting in lower reproductive success in the small-size male group. Female body size was associated with the clutch size, whereas male body size did not affect it. The egg fertilization rate, which was mediated by the male reproductive trait, affected the clutch size; low fertility reduced the clutch size. Our mating experiments highlighted the size-dependent reproductive potential of P. japonicus males, and we recommend that small males should not be used as broodstock in larviculture of this lobster. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of tank colour on growth and survival of taimen Hucho taimen larvae. Larvae (initial weight 0.11 ± 0.01 g, 21 days after hatching) were cultured in the water flow-through system. Fifteen aquaria (200 L per aquarium) were randomly allocated into triplicate groups of 500 larvae. The outsides of the tanks were covered in red, blue, yellow, white, or black sheeting. Larvae were fed eight times a day by hand to apparent satiation. The experiment was conducted for 56 days. The results showed that the specific growth rate was significantly affected by tank colour, which was higher in the yellow tank than that of the tank (black or red) ( P < 0.05). The tank colour did not significantly affect survival, condition factor, and feed conversion ratio among all the treatments ( P > 0.05). The highest feed intake was observed in fish reared in the yellow tank, followed by that of the white, blue, or black tank, and the lowest was in fish in the red tank. In conclusion, the light-coloured tank (yellow or white) was optimum for rearing taimen larvae based on the growth performance. [ABSTRACT FROM AUTHOR]

We studied the effect of dietary microalgae on the fecundity, population development, and fatty acid profile [with focus on the essential fatty acids docosahexaenoic acid (DHA; 22:6ω3) and eicosapentaenoic acid (EPA; 20:5ω3)] of the calanoid copepod Pseudodiaptomus hessei , a potential live food for finfish larvae in aquaculture. Two mono-algal diets, the Tahitian strain of Isochrysis galbana and Rhodomonas salina , and a 50:50 binary diet of the two were fed to copepods. Wild caught copepods were used as a baseline reference point. Copepods fed I. galbana and the 50:50 binary diet had high DHA:EPA ratios and DHA content relative to those fed R. salina . The EPA content of the copepods was similar for all three diets. Copepods fed R. salina had the highest fecundity relative to those fed I. galbana and the 50:50 binary diet. The largest population was obtained when the copepods were fed I. galbana , which differed from those fed R. salina and the 50:50 binary diet. The results of this study showed that the fatty acid composition of P. hessei can be altered by changing its dietary microalgae, and that the copepod can accumulate fatty acids from its diet, especially DHA and EPA. Diet also affected fecundity and population development of P. hessei , so this species represents a potential live food candidate for marine finfish larvae as its nutritional composition and productivity can be manipulated to suit the needs of marine finfish larvae. [ABSTRACT FROM AUTHOR]

Three in vivo experiments were conducted to measure the effectiveness of commercial Bacillus probiotics on survival and development of Litopenaeus vannamei larvae from nauplii 3-4 (N3-4) to zoea 3 (Z3) stages. Experiment I: Nine commercial Bacillus probiotics were individually added to larvae twice at N6 and Z1 at levels of 2, 20, and 100 mg L−1. Only six of nine products at 20 mg L−1 exhibited higher or significantly higher larval survival ( P < 0.05) than the control. Experiment II: Two superior products from the first experiment were administered to larvae with six dose frequencies at 20 mg L−1. For both products, three doses, once at each of N3-4, N6 and Z1 stages, yielded the best larval survival and development rates ( P < 0.05), and these were confirmed by enhanced activities of tryptase and amylase. Experiment III: The isolates of these two products, identified as Bacillus subtilis and Bacillus licheniformis, were delivered to larvae singly at concentrations of 1.0 × 108 and 1.0 × 109 CFU L−1, or at the same concentrations by mixing the two equally. At 1.0 × 109 CFU L−1, B. subtilis exerted more beneficial effects on larvae than B. licheniformis or the mixture. Therefore, the optimal dosage and dose frequency of commercial Bacillus products should be evaluated prior to large-scale application in shrimp hatcheries to avoid futility or even adverse effects, as spore counts and non-bacterial ingredients are key factors influencing the efficacy of Bacillus probiotics. [ABSTRACT FROM AUTHOR]

Conduziu-se este trabalho com o objetivo de avaliar o efeito da utilização de dietas naturais e artificiais sobre o desempenho e comportamento de larvas de pacu (Piaractus mesopotamicus), entre o 2º e o 10º dia de vida. Foram utilizadas 30 caixas plásticas, cada uma com 30 litros de água e renovação contínua, onde as larvas foram mantidas durante o período experimental. Cada caixa recebeu 10 larvas por litro, totalizando 300 larvas/caixa. Foram testados 6 tratamentos, cada qual com 5 repetições. Os tratamentos foram: T1-ração, T2-plâncton, T3-artêmia, T4-plâncton + ração, T5-artêmia + ração e T6-artêmia + plâncton. As larvas foram alimentadas 6 vezes ao dia, nos horários de 4, 8, 12, 16, 20 e 24 horas. A temperatura da água foi mantida constante a 27ºC, o oxigênio dissolvido permaneceu na faixa de 6,16 ± 0,34 e o pH, entre 7,16 ± 0,22. Aos 2, 4, 6, 8 e 10 dias de vida, foram coletadas amostras de 30 larvas para determinação do comprimento total e peso. No final do experimento (10º dia), as larvas que receberam artêmia + plâncton (T6) alcançaram os maiores valores de comprimento total (8,35 mm) e peso corporal (3518 µg), em relação a todas as outras dietas testadas. As larvas devem permanecer em laboratório por um período de 6 dias após a eclosão, recebendo alimento do terceiro ao sexto dia. A partir do sexto dia, as larvas estão com a vesícula gasosa completamente inflada e apresentam nado contínuo.The objective of this research was to evaluate the effect of natural and artificial diets on the development and behavior of pacu (Piaractus mesopotamicus) larvae, between the 2nd and 10th day post hatch. The larvaes were kept in 30L - plastic boxes (n = 30 boxes), in constant flow-through. The larvae density was 10 post-larvae/L (300 larvae/box). Six diets with 4 sampling days (4, 6, 8 and 10 days post-hatch, n = 30 larvae) using 5 repetitions were tested. The diets were: T1- commercial feed, T2- plancton, T3- artemia, T4- plancton + feed, T5- artemia + feed and T6- artemia + plancton. Larvaes were fed 6 times a day: 4, 8, 12, 16, 20 and 24 hours. The water temperature was kept constant at 27ºC, dissolved oxigen was kept between 6.16 ± 0.34 and pH between 7,16 ± 0,22. At the end of the experiment (10th day post-hatch), the larvaes that received diet containing artemia + plancton (T6) were longer (8.35 mm) and heavier (3518 µg body weight), compared to the larvae fed with the other tested diets. The larvae should be in the laboratory for 6 days after hatch, being feed from the 3rd day after hatch. Before the 6th day, the larvae have the gas bladder completely full and swim continuously.

This research represents the first result of studies of the common snook Centropomus undecimalis larvae from broodstock matured in captivity in Brazil. The aim of this study was to evaluate if the inclusion of Acartia tonsa nauplii improves stress resistance of common snook larvae. The larvae were fed with: rotifers Brachionus plicatilis (10 to 15 mL-1); A. tonsa nauplii (0.25 to 0.5 mL-1) and rotifers (5 to 7.5 mL-1), and A. tonsa nauplii (0.12 to 0.25 mL-1). The average percentage of survival of the treatments was 11.9%. At 20 days of age, larvae were subjected to thermal stress. Subsequently, the stress resistance was evaluated. Common snook larvae fed B. plicatilis+A. tonsa reached a higher weight and length (7.5 ± 0.00 mg and 9.1 ± 0.23 mm, respectively) and resisted more heat stress (87.4%) than larvae fed other foods, indicating that the feed mixture is satisfactory as a starter diet for larvae of common snook. However, more research is needed to confirm these results. [ABSTRACT FROM AUTHOR]

Bacterial pathogens are a leading cause of disease in hatchery aquaculture systems and preventative methods such as use of probiotics as feed supplements and water additives are well documented. However, comparisons between the effectiveness of using probiotic water additives over traditional biocontrol methods are less understood. This study assessed the combined effects of ultraviolet (UV) irradiation, O 3 (ozone) and Bacillus spp. as a water additive (probiotic), in the culture of European lobster ( Homarus gammarus ) in a semi-closed recirculation system. Larvae were categorised as zoea stages I–III, megalopa (stage IV) and juvenile (stage V) onwards. Stage I larvae were assigned to one of six treatment groups consisting of 1) O 3 , 2) probiotic, 3) probiotic + O 3 , 4) probiotic + O 3 + UV, 5) O 3 + UV, or 6) probiotic + UV, for 18 days. During stages I–V, growth was measured on 1, 6, 11, 18, 24, and 31 dph (days post hatch), and survival was measured on 1, 18, 24 and 31 dph. Bacterial counts of pathogenic Vibrio spp. in culture water were measured at 1, 4, 9, 14, and 18 dph. Lobsters were also exposed to a physiological fitness test (low salinity challenge) at stage IV, 7 days post treatment. Results showed that O 3 is comparatively more beneficial than probiotic with increased LWG (live weight gain) in the O 3 treatment over probiotic between stage IV and V (> 5 mg). Survival rates were ~ 10% higher in the O 3 treatment group than probiotic treatment group on day 18, then ~ 5% and ~ 4% higher on days 24 and 31. Lobster biomass on day 18 was ~ 60% higher in the O 3 treatment than probiotic treatment and 116% higher on day 31. Total Vibrio spp. present in the O 3 treatment was 0.05% of the total in the probiotic treated culture water (day 18). Results between UV treatment groups showed significantly lower numbers of Vibrio spp. present in probiotic + O 3 + UV culture water 4 dph than O 3 + UV (~ 10 fold higher) or UV + probiotic (~ 15 fold higher) and by day 18 probiotic + O 3 + UV was significantly higher than O 3 + UV (~ 8 fold higher). Osmoregulatory challenge test resulted in no significant differences in physiological fitness between any treatment groups. The present study shows the effectiveness of O 3 in aquaculture facilities for control of pathogens in the rearing of European lobster over either a probiotic water additive (at 3.75 × 10 7 CFUs L − 1 ) or UV irradiation. [ABSTRACT FROM AUTHOR]

For consistent seed production, better understanding of larviculture and rearing techniques is crucial to maximize production of high quality and healthy larvae of cultured species. There are many different larval rearing methods in the world due in part to the geography, climatic patterns, species culture, and feeding regimes. This review provides available information on the present status of hatchery techniques in aspect of larval production, identifies husbandry techniques, recognized the main bottlenecks of current hatchery operations and identify likely future technique for consistent production of blue swimming crab, Portunus pelagicus. It is important to simplify larval rearing methods to develop easy-to-use and efficient systems for the mass rearing of healthy crabs. The information on this review will be useful as a guideline to culture others Portunid crab as well as a reference to the academician, aqua-culturist, and the industry that indirectly support the sustainable aquaculture development for P. pelagicus crab. [ABSTRACT FROM AUTHOR]

The sodium adsorption ratio ( SAR) is used to describe the ratio of sodium to calcium and magnesium in water that is very important in both aquaculture and agriculture. SAR treatments including of 20, 30, 40, 50 and 60 were adjusted in 10-L containers. Initial larval density was fixed at 100 larvae L−1 and during the culture period, various larval quality parameters were evaluated. Our findings illustrated that at initial stages of larval development, different SAR treatments affected the larval condition index ( LCI), but no influences on larval stage index ( LSI) were apparent. Importantly, this process at the final larval stages became reversed. In addition, survival at SAR 30 was 12.4% greater than among any other treatments. The highest larval resistance to stress (191 ± 5 ppm), as measured by the 24-h LC50 formalin test also was observed for SAR 30, at the 11th larval stage. Analysis indicated that calcium absorption during larval developmental stages is affected by SAR levels in the environment and also showed that the optimal SAR treatment was 30 for Macrobrachium rosenbergii larviculture in inland hatchery brackish water. According to our findings and desired SAR for the environment and agricultural soil (<15), effluent of M. rosenbergii inland hatcheries must be treated at least two times by dilution and adding calcium and magnesium salts. [ABSTRACT FROM AUTHOR]

The African River prawnMacrobrachium vollenhoveniiis the largest of the local Palaemonidae prawns along the Cameroonian coast and an important target species for fisheries and aquaculture. A preliminary study on larviculture of this species was carried out at the IRAD-AQUASOL hatchery in Kribi, Cameroon. Berried femalesM. vollenhoveniiwere obtained from the Lobe and Lokoundje Rivers in the Southern Region, typical Lower Guinea rainforest streams. The larval rearing system consisted of a single recirculation system of four 65 L cylindrical plastic containers connected to a submerged biological filter container (65 L). Experiments were conducted three times in the same condition, with two batches of larvae reared separately in duplicate per experiment, at a density of 40/L, temperature 26°C, and salinity 16%. Larvae were fed from 1 day after hatching until metamorphosis to postlarvae (PL) with newly hatchedArtemia nauplii, three times daily at the rate of 5 nauplii per mL water. The number of newly hatched larvae per female body weight unit was not affected by the female size and ranged between 531 to 1349 larvae g−1. The six batches succeeded from hatching to metamorphosis, and the 11 distinct larval stages described forM. rosenbergiiwere found. Larvae in all the batches developed more or less at the same pace up to stage V. However, a clear difference in the timing of appearance of the developmental stages was observed between batches and individuals of the same batch during the subsequent stages. The transition from stage V to stage VI and from stage IX to stage X was longer than the passage to other stages and seems to be the critical rearing period ofM. vollenhovenii. From day 20 onward to sampling, the larval stage index (LSI) showed that larval development of the batch 1 was significantly faster than for all other batches. The time for first appearance of postlarvae was variable between batches (41–74 days), and batch 1 larvae passed through metamorphosis within a shorter span of time (41 days). Survival up to postlarvae was variable among batches, ranging between 3%–9%, and was better in batch 1 (9.31 ± 1.09). The general poor performance in terms of survival and metamorphosis rates of larvae seems to be related to the wild condition of broodstock. To improve performance of larvae, domestication of stock may be necessary. This result is the first recorded success in larviculture ofM. vollenhoveniiin Cameroon. [ABSTRACT FROM AUTHOR]

In recent years, a number of South American freshwater fish have gained increasing attention for their potential in aquaculture, not only because of their excellent performance in farming systems but also to meet the high consumer demand for these species due to declining fishery resources. Many South American freshwater species are migratory and produce altricial larvae, with a small amount of yolk reserves. Unlike precocial freshwater species and altricial coldwater marine fish, these freshwater fish investigated have rapid yolk depletion and metamorphosis. Specific studies on the initial development of South American fish are scarce and fragmented. One of the most widely studied species is the pacu ( Piaractus mesopotamicus ), farmed in warm continental waters. In the present review we compile new and published data on the initial development of pacu, including morphogenesis of the skeletal, muscle, digestive and sensory systems; compare it to other Neotropical species; and discuss the importance of this information to develop larviculture protocols. When pacu larvae exhaust yolk reserves, they initiate a new form of interaction with the environment, becoming exclusively exotrophic. This type of interaction is made possible by the rapid development of sensory, skeletal, locomotor and digestive structures. In addition to understanding fish ontogeny, studies on larval development are necessary to improve farming systems and larviculture techniques aimed at producing high-quality juveniles in aquaculture. [ABSTRACT FROM AUTHOR]

The effects of the most important factors (food quality and quantity, temperature, and salinity) on the production of the harpacticoid copepod Amphiascoides atopus Lotufo & Fleeger, originally described from a mass culture system at the Department of Zoology and Physiology of the Louisiana State University at Baton Rouge, were evaluated to ascertain potential yields. For aquacultural purposes, it is important to assess these factors for laboratory-controlled conditions. Feeding treatments were not significantly different between monospecific ( Chaetoceros muelleri, Isochrysis sp., and Nannochloropsis oculata) and mixed diets (all three of the mentioned diets in ratios of 1:1:1) (527.2 ± 68.3 to 404.4 ± 160.6 organisms L−1). Copepods fed diets of 320 cells μL−1 (539.6 ± 115.8 organisms L−1) showed the highest mean egg production. Our results demonstrate that a temperature of less than 20°C (15 ± 3.5 organisms L−1) significantly affected the final mean population counts. No statistical differences were observed at 24, 28, and 32°C with productions varying between 330 ± 67.4 to 527 ± 101.3 organisms L−1. Of all the salinity levels tested, the highest population densities were recorded at 32 psu (983.0 ± 78.8 organisms L−1). Identifying the correct copepod species as live prey for larviculture is also considered important so that the appropriate size and characteristics of the food can be administered. These findings suggest that the copepod A. atopus can serve as a good potential live feed for larviculture. [ABSTRACT FROM AUTHOR]

The Nile tilapia is among the most cultivated tropical fish in the world, yet little is known about the variations in reproductive characteristics among different strains. There is an interest in evaluating the reproductive performance of females of three tilapia strains. All strains were represented in equal proportion ( n = 225), being named as Supreme (SUP), Premium Aquabel (PA), and Chitralada (CHI). These fish were cultivated for 7 weeks in the Aquabel Pisciculture Station (Brazil), from January to March 2011. The PA was the largest strain, with the highest values in all the morphometric parameters we analyzed (weight, total length, standard length and body depth). Among the evaluated reproductive parameters, the PA strain differed significantly from the other two in number and weight of eggs/female, volume of eggs/spawn and number of eggs/kg of fish. The percentage of non-spawning females in the SUP and CHI strains differed significantly from one another, while results for PA showed intermediate values and no significance compared to the other strains ( P > 0.05). Among the reproductive parameters analyzed, the percentage of spawned females/week, more than one spawns during 7 weeks, and hatching rate showed no significant differences between strains ( P > 0.05). There was a significant correlation ( r = 0.69) between water temperature and percentage of spawned females/week. When evaluating the interval between two consecutive spawns, we observed that periods of 21 days were the most frequent in all strains. In conclusion, the strain that showed the best results in all morphometric and in most reproductive parameters we evaluated was the PA. [ABSTRACT FROM AUTHOR]

Abstract: The optimum concentrations of calcium and magnesium for the combinations tested in hatchery water for Macrobrachium rosenbergii larviculture were evaluated. Experiments were conducted in two stages: in the first, triplicate treatments of calcium (120, 180, 240 and 300ppm) and magnesium (300, 400, 500 and 600ppm) were separately evaluated in a closed recirculating system (60-l). During the second stage, combinations of the two best calcium and magnesium concentrations determined in the first stage were compared. This stage used a static system (10-l) with minimal water exchange. In both stages, initial larval density was fixed at 100 larvae l−1 and larval stage index, larvae dry weight, survival and time of the first postlarvae appearance were the determined parameters. The results of the first stage revealed that increasing concentrations of Ca and Mg showed a non-linear and a linear response respectively. According to these results, concentrations of 180 and 240ppm calcium and concentrations at 300 and 400ppm of magnesium were evaluated during the second stage of the investigation. In this stage, the results showed that after the 6th stage of larval development, interactions between both calcium and magnesium affected (P <0.05) the larval quality parameters. The combination of these factors showed that a balance of 240ppm calcium and 300ppm magnesium with Mg/Ca ratio about 1.25 are optimal for larviculture. This balance at 30days post hatch showed the highest larvae survival (40±2.6%) at least 15.4% higher than the other treatments. [Copyright &y& Elsevier]

Abstract: Research on sea slugs production has steadily increased in the last decades as a result of their use as model organisms for biomedical studies, bioprospecting for new marine drugs and their growing demand for academic research and the marine aquarium trade. However, standardized methods for culturing sea slugs are still limited to a reduced number of species. The main bottlenecks impairing sea slugs aquaculture are the lack of knowledge on suitable larval diets and settlement cues that can induce metamorphosis in competent larvae. Additionally, the stenophagous feeding regime displayed by several species requires the collection and/or culture of their prey, which commonly impairs large-scale production. Nevertheless, significant breakthroughs have been achieved in recent years through the development of innovative culture techniques. The present review summarizes the major issues impairing the culture of sea slugs and presents relevant biological and ecological data that can assist on the development of suitable culture protocols. Information on the most suitable husbandry, larviculture and grow-out techniques are critically discussed, with emphasis to their application on some of the most relevant groups of sea slugs from an academic and commercial point of view: sea hares (Aplysia spp.), nudibranchs (e.g., the marine ornamental species Aeolidiella stephanieae) and the “solar powered” sacoglossan (e.g., Elysia spp.). [Copyright &y& Elsevier]

Largemouth bass (LMB) Micropterus salmoides fry do not accept prepared diets at first feeding. Fry are initially reared in fertilized ponds on natural live foods until large enough to be feed trained. Unpredictable weather patterns and depletion of natural forages can affect nursery pond survival. A series of experiments was conducted to investigate the use of Artemia nauplii prepared diets and optimal feeding schedules to raise LMB fry from first feeding through habituation to a commercial dry diet. In Studies 1, 2, and 3, swim-up fry were transferred to a recirculating system and stocked into either 3-L (Studies 1 and 2) or 10-L (Study 3) acrylic aquaria. Study 1 screened candidate diets to evaluate whether LMB fry could be transitioned directly to prepared diets or if they required live foods. In Study 2 the optimum duration for feeding live Artemia (1, 2, or 3 weeks) and the appropriate size of commercial diets (<200 or 200-360 μm) were evaluated. Study 3 was designed to identify the best transitional feed. Results from Study 1 indicate that fry fed Otohime-A (<200 μm) and decap-sulated Artemia cysts performed better than those fed other diets tested. However, survivals were low (6%-8%) indicating a need for live feed initially. In Trial 2, fry fed live Artemia nauplii for two weeks and then transitioned to a 200-360 [im diet (Otohime-B) performed better than other diet combinations tested. In Study 3, survival was significantly higher in treatments using decapsulated Artemia cysts or Otohime-B as transitional diets between initial live Artemia feeding and trout starter. These data indicate that LMB fry can be successfully raised from first feeding to fully habituated to a commercial trout starter by feeding live Artemia nauplii for two weeks, followed by a gradual transition to either decap-sulated Artemia cysts or Otohime-B for one week, then gradually transitioning to trout starter. Surviving fish were easily transitioned to commercial floating feed (Study 4). This protocol yielded survival rates of approximately 70% and may improve the reliability of LMB fingerling production by eliminating the outdoor nursery pond phase. [ABSTRACT FROM AUTHOR]

Abstract: Several marine and freshwater predatory copepods (Labidocera, Pontellopsis, Mesocycops and Acanthocyclops) exhibit a wide dietary niche, ranging from protists, rotifers, cladocerans, copepods, to insect and fish larvae. Predation-induced fish larval mortality in natural environments and hatcheries reduces larval abundance and may limit fish recruitment. However, few studies quantified the losses incurred by copepod predation. Therefore, this study quantified vulnerability, susceptibility, and loss of two crucial fish, Labeo rohita and Catla catla, to cyclopoid predation in relation to larval age and body length under laboratory conditions. In addition, we compared susceptibility of fish larvae to the copepod (Mesocyclops thermocyclopoides and Mesocyclops aspericornis) predation in the laboratory, based on probability of survival after attack in relation to age and size of the larvae. We also evaluated the modulatory role of alternate zooplankton species as common prey of fish larvae and copepods. Both cyclopoid species were able to subdue and kill both species of fish larvae. The two cyclopoid species did not differ considerably in their predation efficiency on larvae; the larvae of C. catla and L. rohita did not differ considerably in their respective vulnerability to cyclopoid predation. In both species of fish larvae, the copepod-imposed mortality was inversely related to larval age (R2 ≥0.97) and body length (R2 ≥0.93). The effect of alternate prey on copepod-imposed mortality was species-specific to prey. The presence of Paramecium caudatum, Brachionus calyciflorus and Ceriodaphnia cornuta resulted in decreased mortality of fish larvae by the copepod; however, the larvae were more susceptible to copepod predation in the presence of either Hexarthra mira or Daphnia similoides as alternate prey. The copepod-induced mortality of carp larvae was recorded, even in multispecies prey environment; however the mortality was considerably less than that in control. Overall, the maximal reduction (40–100%) in copepod-imposed larval mortality was achieved by the Rotifera B. calyciflorus, followed by the Cladocera C. cornuta and ciliate P. caudatum. The modulatory effects of the presence of alternate prey were more pronounced after fish larvae reached 4days post hatch (dph). The susceptibility of carp larvae to copepod predation differed ontogenetically with maximal susceptibility between 0 and 4dph. Threshold level for copepod-imposed mortality was estimated with bilinear model, which ranged from 5.2 to 8.4dph and 6.8 to 7.8mm body length. Our results provide insight and valuable inputs for enhancing the efficiency of nursery rearing. [Copyright &y& Elsevier]

In spite of the growing interest and success obtained using cultured-copepods, their use in marine aquaculture remains sporadic. Besides, mass culture of several marine copepods has been well established by several authors. However, the upscale of copepod cultures to commercial levels is still a challenge. The practice of using wild copepods from natural ponds which thus increases the risk of parasitic infections of most species has limited their application in aquaculture. The present paper thus emphasizes on recent research efforts focused on the use of chemical treatments and freeze-thawing methods to eradicate procercoids from copepods. Research efforts focused on copepod culture systems which subsequently improved and refined their culture in marine fish larviculture are also well discussed. Advances in the use of copepod eggs as potential source of nauplii for marine fish larvae with special emphasis on the viability, storage conditions and biochemical compositions of the copepod eggs are underscored. Additionally, recent advances in the biochemical compositions (protein, amino acids, pigments, and vitamins) of copepods, which has received relatively little attention compared to researches on the lipid and fatty acid compositions are well emphasized. Specific recommended areas for further research are also proffered. [ABSTRACT FROM AUTHOR]

The performance (growth and survival) of diploid and triploid jundia, Rhamdia quelen, was evaluated at six different stocking densities (10, 60, 110, 160, 210, 260 larvae/liter) during 31 days after rearing in an intensive larviculture system. Triploid fish exhibited a significantly higher survival rate than diploids at all stocking densities (27.1 ± 4.3% vs. 12.1 ± 3.3%; P < 0.01). Survival was not affected by stocking density (P > 0.05). Length gain was not affected by either ploidy or stocking density. Diploid fish gained more weight than triploids (P < 0.05), though this difference could result from lower fish densities in diploid treatments resulting from the higher mortality rate of diploid fish. This hypothesis is strengthened by the higher biomass present in triploid treatments (P < 0.01). [ABSTRACT FROM AUTHOR]

In recent years, an increasing interest in the farming of marine 'white' fish, such as cod, has been observed in the aquaculture industry. One species being considered for aquaculture development is whiting ( Merlangius merlangus L. ). With little data being available on the domestication of this species, our study aimed to characterize spawning behaviour and rhythmicity in captive broodstock and provide original data on egg incubation, embryonic development and larval rearing. The results observed through video recording showed that spawning mainly occurred at night with active courtship behaviour. Daily egg batches were collected from two separate spawning seasons, with an average fertilization success declining from 77% to 53%. Time to hatch was inversely related to the incubation temperature and occurred after 78 degree-days (9 days at 8 °C), with emerging larvae ranging in size from 3.3 to 3.46 mm total length and hatch success ranging from 48.3% to 99.9%. In comparison with a clear water environment, a green water regime during the first days of larval rearing significantly improved larval growth and survival. These results are the first to describe spawning activity, early development and larval performances in whiting and are promising for the potential future development of whiting aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: Selected rotifer enrichment diets were compared on the basis of growth, survival, and fatty acid content of larval Florida pompano, Trachinotus carolinus L. Two 9-day larval rearing trials were conducted using a recirculating aquaculture system. In Trial 1, two microalgae concentrates (Isochrysis sp., ISO; and Pavlova sp.), a semi-moist paste (Protein Selco Plus, PS+), and a combination of the three diets were compared. In Trial 2, PS+ and three dry enrichment diets (Ori-Green, OG; Protein HUFA, PH; and AlgaMac 3050, AM) were compared. Larvae were fed rotifers 4 times daily at a rate of 2.5 rotifers/ml/feeding at 2–9 days post-hatch (DPH). Although larval growth in both trials was likely influenced by differences in culture density resulting from variable survival, in Trial 1 at 9 DPH standard length (SL) of larvae fed Pavlova-enriched rotifers (4.60±0.39 mm, mean±SD) was greater (P <0.05) than that of larvae fed rotifers enriched with ISO (4.29±0.48 mm); and the combined treatment (4.31±0.48 mm) and body depth (BD) of larvae fed Pavlova-enriched rotifers (1.21±0.16 mm) was greater than that of larvae fed rotifers enriched with the combined treatment (1.08±0.18 mm). In Trial 2 at 9 DPH, SL and BD of larvae fed rotifers enriched with PH (5.00±0.23 and 1.24±0.12 mm, respectively) was greater than that of larvae fed rotifers enriched with other diets. Survival of larvae fed rotifers enriched with PS+ was highest in both Trial 1 (24.1±10.2%) and Trial 2 (34.4±1.6%) and was significantly greater than that of larvae fed rotifers enriched with Pavlova (7.3±1.6%) and the combined treatment (6.0±1.6%) in Trial 1 and larvae fed rotifers enriched with PH (21.8±6.3%) and AM (14.1±4.9%) in Trial 2. While lipid content and fatty acid composition of PS+ enriched rotifers closely resembled that of pompano yolk-sac larvae, n −3 HUFA content of PS+ enriched rotifers as well as larvae fed PS+ enriched rotifers was not significantly greater than that of other diets tested in both trials. [Copyright &y& Elsevier]