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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]

The nutritional characteristics of microalgae affect the growth, survival and fatty acid composition of sea urchin larvae. This study aimed to evaluate the influence of nutritive characteristics of single microalgal diets in Paracentrotus lividus (Lamarck, 1816) larval development, growth, and condition. Larvae of P. lividus were fed with three monospecific microalgal diets, Rhodomonas sp. (Rho), Dunaliella tertiolecta (Duna) and the diatom Chaetoceros calcitrans (Chae), and their development and growth were analysed until competence. Additionally, the fatty acid (FA) profile of larvae was analysed at competence and compared with the FA profile of the correspondent diet. The three groups of larvae attained competence simultaneously with differences in growth performance. The larvae fed with Chae attained the largest stomach and the shortest post‐oral arm. The larvae were able to accumulate long‐chain polyunsaturated fatty acids (PUFA), such as docosahexaenoic (DHA, C22:6n − 3), eicosapentaenoic (EPA, C20:5n − 3) and arachidonic (ARA, C20:4n − 6) acids, either by assimilation and retention of dietary FA or by the synthesis from α‐linolenic acid (ALA, C18:3n − 3) and linoleic acid (LA, C18:2n − 6). Furthermore, the low DHA/EPA ratio and high EPA/ARA and n − 3/n − 6 ratios of Rho and Chae and the high levels of the β‐carotene present in Chae improved larval growth and development. In conclusion, the results indicated that of the three microalgal diets tested, C. calcitrans provided important nutritional characteristics, especially in terms of FA composition and carotenoids, improving P. lividus larval growth and condition. [ABSTRACT FROM AUTHOR]

In this work, we examined the effects of rapid changes in salinity on the availability (mobility and swimming) of the prey rotifer Proales similis. Rotifers were transferred as follows: 5 to 15, 25 and 35 (T1); 15 to 5, 25 and 35 (T2); 25 to 5, 15 and 35 (T3) and 35 to 5, 15 and 25 ppt (T4) during 1–240 min. Results showed that in T2 and T3, the percentage of mobile rotifers in the water column recovered up to 100% after 15 min. At T1 and T4, mobility regained slower at 35 and 5 ppt respectively. All individuals transferred at 15 and 25 ppt maintained their mobility above 93% after 15 min. In general, swimming speed ranged from 0.37 to 0.65 mm s−1 and was higher at 15 ppt and lower at 35 ppt. In all salinities, swimming increased with time and recovered better in T2 and T3. These data suggest that P. similis can acclimate to a wide range of salinity gradients in the short term (1–240 min). According to the literature and our results, P. similis has a greater tolerance to sudden salinity changes than brachionid rotifers used traditionally in fish larviculture. [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]

This work evaluated the effects of different carbon/nitrogen (C/N) ratios in the larvae and fry culture of Piaractus orinoquensis in biofloc system on the water quality, proximate analysis and growth performance. The experiment was conducted in two stages: (a) larval stage from 0 to 12 days post stocking (DPS) and (b) fry stage from 13 to 24 DPS, at a density of 10 larvae/L. Three groups of C/N ratios were evaluated as follows: T1: 10/1 ratio, T2: 15/1 ratio and T3: 20/1 ratio, each treatment with three replicates. Both in the larval and fry culture, total ammonia nitrogen (TAN) and nitrite were higher in the T2 and T3 treatments, while the nitrogen removal in T1 treatment was more efficient, resulting less TAN, nitrite and higher nitrate. However, the water quality parameters in all treatments were within the appropriate ranges for fish culture in biofloc. T2 treatment was nutritionally better, presenting higher levels of protein, lipids and energy. In both stages, P. orinoquensis survival and final weight were significantly higher in the T2 treatment. In conclusion, P. orinoquensis larvae and fry culture in biofloc is viable, improving the survival and growth at a C/N ratio of 15/1. [ABSTRACT FROM AUTHOR]

Temperature is a limiting factor to the development of fish eggs and larvae. The aim of this study was to define the optimal temperature for egg incubation, larval survival and development of Sardinella brasiliensis larvae. Eggs were obtained by natural spawn and collected after the blastopore enclosure. Fertilized eggs were incubated at 17, 20, 23, 26 29 or 32°C in beakers. Larval development (200 eggs L-1), hatching and survival rates (100 eggs L-1) and RNA/DNA ratio were evaluated. The best temperature for hatching was 28°C, the best survival rate was obtained at 24.7°C, and 100% of the larvae died at 18.4°C. The time of mouth opening (24 to 51 h) and moment of eye pigmentation (24 to 45 h) varied with temperature. No significant difference was found in the RNA/DNA ratio between the treatments, indicating the nutritional status of the larvae. The interval between 24.7 and 28°C resulted in a better hatching rate and larval survival. Water temperature affected the hatching rate, survival and morphometric development of S. brasiliensis larvae. [ABSTRACT FROM AUTHOR]

The Asian catfish, Clarias magur, is an endangered fish species, which is immensely important due to its high commercial value in India and other South‐East Asian countries. Various anthropogenic activities and natural habitat loss have greatly impacted the biodiversity of C. magur in natural water bodies, leading to the addition of this species to the endangered species list. The development of captive spawning and selection of an ideal broodstock size are critical steps to maximize the efficiency and robustness of conservation efforts for the catfish. An induced spawning experiment was conducted to ascertain the reproductive performance, egg and larval quality of catfish broodstock from fish with varying body weights. Five female C. magur broodfish from each of the following size ranges, F65 (65 ± 5.0); F130 (130 ± 7.9), F180 (180 ± 3.5) and F250 (253 ± 9.7g), were selected along with male broodfish with the same body weight range. The present study's results revealed that the stripping response was higher (F = 2.06; p = 0.15) for medium‐sized F180 magur female broodstock; however, no significant differences were observed for this group. Total (F = 20.79; p < 0.001) and relative fecundity (F = 3.09; p = 0.057) were found to be significantly higher for F250 and F65 broodfish respectively. Total fecundity had a strong significant positive correlation (r = 0.99; p = 0.012) and also had significant linear regression relation (R2 = 0.98; p = 0.012) to maternal size. Hatching rate was observed to be significantly higher (F = 7.82; p = 0.002) for the medium‐sized broodfish, F130. The medium‐sized broodstock of 130–180 g had strong positive influence on the growth and survival of the progeny, while F250 broodfish produced poor‐quality larvae, which resulted in reduced larval growth performance and survival. Specific growth rate (SGR) and thermal growth coefficient (TGC) were also found to be significantly higher for F130 female broodstock. Hence, the selection of medium‐sized (130–180) or 1‐ to 2‐year‐old female broodstock had a significant effect on the reproductive performance, egg and larval quality of magur in captivity. The results from this study can be utilized as helpful and practical information enhancing selection protocols for the hatchery operators to select ideal broodstock based on size, enabling the production of viable egg and larvae in indoor conditions and a scalable seed production system. [ABSTRACT FROM AUTHOR]

In the present study, the digestive enzyme activity during larval development in L. peru reared under intensive culture conditions was evaluated. The results revealed that L. peru larvae have the necessary enzymes to digest proteins, lipids and carbohydrates when nutritional reserves have been depleted at the onset of the exogenous feeding at 3 days after hatching (DAH) or 78 degree‐days (DD). The activities of the digestive enzymes follow patterns similar to those previously reported in other related species. As in other marine fish larvae, the amylase specific activity decreased during larval development of L. peru. At 25 DAH (650 DD), the specific activities of lipase, alkaline phosphatase and acid phosphatase declined, while the specific activities of pepsin, trypsin and chymotrypsin increased. In contrast, the individual activity of all enzymes steadily increased with development. The time required to reach the maximum activity varies, suggesting a relative importance of different digestive enzymes during the different developmental stages of the digestive tract. In our study, the highest activity was reached by amylase at Stage I and early Stage II (3–11 DAH or 78–286 DD), by lipase and both acid and alkaline phosphatases at the end of Stage II (18–22 DAH or 468–572 DD), and by trypsin, chymotrypsin and acid protease at Stage III (25 DAH or 650 DD). This study provides new data on the digestive physiology of larval L. peru that are particularly pertinent to early weaning and nutritional physiology, and that may be useful in the larval culture of this species. [ABSTRACT FROM AUTHOR]

Temperature is a limiting factor to the development of fish eggs and larvae. The aim of this study was to define the optimal temperature for egg incubation, larval survival and development of Mugil liza larvae. Artificial fertilization was performed with manual extrusion of oocytes and semen. After the blastopore enclosure, fertilized eggs were incubated at 17, 20, 23, 26 or 29°C in beakers. Larval development (200 eggs L−1), hatching and survival rates (100 eggs L−1) and RNA/DNA ratio were evaluated. The best temperature for hatching is 23.2°C and at 23.9°C was obtained the best survival rate. At 16.5°C, 70% of the larvae died, and at 28.4°C, mortality was 40%. The time of mouth opening (48 to 72 h), moment of eye pigmentation (36 to 64 h) and yolk sac absorption (42 to 48 h) varied with temperature. No significant difference was found in the RNA/DNA ratio between the treatments, indicating the nutritional status of the larvae. The interval between 23.2 and 23.9°C resulted in a better hatching rate and larval survival and had more efficient yolk sac consumption. Water temperature affected the hatching rate, survival and morphometric measures of M. liza larvae. [ABSTRACT FROM AUTHOR]

The development of sustainable methods for sea urchin juvenile production is currently constrained by high mortality rates during larval growth and the high costs of larval rearing systems management. With the aim of developing a method for the production of juveniles of the purple sea urchin Paracentrotus lividus in a medium‐scale recirculating system, the present study focused on the effects of high stocking densities on larval growth. Plutei larvae were reared at three different densities (up to 7 ind/ml) in a semi‐static culture system. Larval survival and metamorphosis success were evaluated in order to identify the most effective density range. The highest metamorphosis rates (80%–95%) were obtained at 4 and 7 larvae/ml. These results are comparable with (and in some cases higher than) those reported for the same species at much lower larval densities. In conclusion, the rearing conditions tested here show for the first time that a significantly higher (4 ind/ml) stocking density than those of traditional P. lividus rearing methods (based on large volumes and low densities) can be adopted, thus supporting the feasibility of an increase in the final output of competent larvae with no increase in rearing volumes. [ABSTRACT FROM AUTHOR]

We evaluated the effect of light intensity on survival rate and zootechnical performance in matrinxã larvae (Brycon amazonicus) that is an important species for fish farming in the Amazon region. For this, the larvae were submitted to three experimental stages: Stage I—10–72 hr after hatching (HAH), Stage II—72–168 HAH and Stage III—168–288 HAH. The animals were submitted to three treatments of different light intensities: low (±20 lx), intermediate (±200 lx) and high (±2,000 lx). The low light intensity increased the survival rate in 24, 48, 72, 120, 168 and 288 HAH. The size of the animals was homogeneous in 72 and 168 HAH in the low and intermediate treatments. The high light intensity increased the zootechnical parameters in 288 HAH. We suggest the use of low light intensity in the initial periods of observation (24 and 48 HAH) to reduce aggressiveness and increase the survival and homogeneity of the animals. On the other hand, it is possible to suggest an increase in the light intensity in the final period of observation (288 HAH), as the increase in intensity stimulated growth and affected the survival rate of the matrinxã larvae. [ABSTRACT FROM AUTHOR]

The study evaluated productive performance of larvae Nannostomus beckfordi submitted to feeding management (Experiment one) and different stock density (Experiment two) in captivity conditions. The first experiment evaluated feeding rate (100 and 200 nauplii of artemia larvae−1 day−1) and feeding frequency (2 and 4× per day). Second experiment evaluated different stock density (1, 5, 10, 20, 40 larvae per litre). At the end of 15 days, for both experiment, the survival and productive performance such as total length (TL), final weight (FW), specific development rate (SDR), specific growth rate (SGR), uniformity for weight (UW) uniformity for length (UL) and relative condition factor (Kr) was determined. For the main results, there is no significant difference to the rate and feeding frequency. The stock density has no significant difference for UW, Kr and survival. Nonetheless, a reduction in the TL, FW, SDR, SGR and FW with the increase in density (20 for 40 larvae per litre) was observed. Thus, for this species Nannostomus beckfordi during to initial stage using exogenous feeding, it is recommended 20 larvae per litre fed with 100 nauplii per larvae having two meals per day. [ABSTRACT FROM AUTHOR]

A 49‐day rearing trial was conducted to investigate the effects of Pseudoalteromonas sp. F15 on growth, survival, digestive and immune‐related enzyme activities in larval and juvenile Yesso scallop, Patinopecten yessoensis. Larvae (Day 2 post‐fertilization) (d2 PF)) were provided with a diet only of microalgae (control) and supplemented with F15 at final concentrations of 1×104 and 1×106 cells/mL, respectively. Results indicated that the specific growth rates and survival rates of umbo larvae (d13 PF), crawling pediveliger larvae (d28 PF) and juveniles (d51 PF) fed the F15 supplementation diets at 104 and/or 106 cells/mL were significantly higher than those fed the diet of microalgae. Larvae and juveniles fed 104 and/or 106 cells/mL F15 supplementation diets showed a significant increase in pepsin, amylase and cellulase activities compared with the control group. The lysozyme, superoxide dismutase and catalase activities of larvae and juveniles fed the F15 supplementation diets at 104 and/or 106 cells/mL significantly increased compared to those fed the diet of microalgae. In addition, F15 protected juveniles against challenge with Vibrio splendidus. These data suggest that F15 can be useful in scallop larviculture. [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]

Natural spawning, early development and larviculture of the ornate goby Istigobius ornatus in captivity were studied for the first time. I. ornatus spawned 46 times from 31 October 2013 to 31 October 2014. Fecundity ranged from 246 to 10,214 eggs per clutch, with an average hatching rate of 77.8% ± 9.9% (M ± SEM). Fertilized eggs (1.31–1.54 × 0.46–0.50 mm in diameter) were adhesive demersal and oval‐shaped. Embryonic development lasted 84 hr at 27.5 ± 0.5°C. Newly hatched larvae [2.12 ± 0.04 mm in total length (TL)] transformed to the juvenile stage completely when TL was 7.79 mm. Effects of different water temperatures (24, 28 and 32°C) and salinities (10, 15, 20, 25, 30, 35 and 40 g/L) on per cent survivals (%) and survival activity indices (SAIs) were tested. Survival was not significantly different under different temperatures; SAIs was significantly higher at 28°C. Larvae showed the significantly higher survival and SAIs at salinities 10–30 g/L than at 35 and 40 g/L. Effect of different prey densities on survival was significantly higher in 7 days post hatch larvae fed 20 and 30 rotifers/ml. These findings could guide future programs in captive breeding technology development and commercial production of other marine ornamental gobies. [ABSTRACT FROM AUTHOR]

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]

Abstract: Adequate enrichment of live prey like Artemia, naturally deficient of essential highly unsaturated fatty acids (HUFA), such as docosahexaenoic acid (22:6n‐3, DHA), is critical for the rapidly developing tissues, survival, normal development and production of good‐quality fingerlings. The aim of the study was to evaluate the effects of a pulse (10–30 dah) of Shewanella putrefaciens Pdp11 (2.5*107 cfu/ml) using Artemia metanauplii as live vector, on its proper lipid profiles and resultant Solea senegalensis body composition and performance. Probiotic administration significantly increased total lipids and specifically n‐3 HUFA levels in Pdp11‐enriched Artemia. The live prey lipid modulation was also reflected in the total lipid contents and fatty acid profiles of Pdp11 sole specimens, which achieved a higher growth performance. A fatty acid multivariate principal component analysis confirmed a neat separation of two groups corresponding to Control and probiotic fish for each age sampled (23, 56, 87 and 119 dah). In addition, a further SIMPER analysis highlighted that the Pdp11 Artemia effect on sole lipid profile was different for each fatty acid and was gradually diluted with age. Results suggest an ability of Pdp11 strain to produce n‐3 HUFA as an effective tool for fish marine larviculture optimization. [ABSTRACT FROM AUTHOR]

Abstract: The study investigated the combined effect of weaning from live feed to a commercial dry pellet at 10, 15, 20, 25 or 30 days posthatching (dph) and co‐feeding for 1, 3 or 6 days on survival and growth of Coregonus peled larvae. Additional groups fed only live Artemia sp. nauplii (ART), and only Biomar LARVIVA ProWean 100 (DRY) were included. A final survival rate of 66.4%–85.5% was observed in groups weaned after 20 dph. Final body weight (BW) and total length (TL) were significantly lower in groups weaned at 10 and 15 dph, regardless of the duration of co‐feeding. Larvae reached 29–37 mg BW and TL of 17.7–19.0 mm in groups weaned at 20, 25 and 30 dph. The recommended minimum duration of feeding with live food, based on these results, is 20 days. Based on the significantly higher yield of larvae weaned after 20 dph irrespective of co‐feeding duration, it can be concluded that abrupt weaning to dry food after 20 days of feeding with live prey can provide adequate production while reducing the effort and costs associated with live feed. [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]

Feeding copepods during early larval culture stages of marine fish has proven to be advantageous for growth and survival of marine finfish larvae. However, commercial availability of most copepods is limited; thus, there is an impetus to evaluate promising copepod species to meet the diverse dietary demands of various marine fish. The marine cyclopoid copepod, Oithona colcarva, was isolated out of zooplankton samples taken from waters within Tampa Bay, Florida. Once isolated, trials were conducted to determine the appropriate culture parameters for producing nauplii to feed marine fish larvae. The effects of temperature (22°C, 26°C and 30°C), salinity (15, 20, 25, 30 and 35 g L−1), stocking density (0.5, 1.0, 2.0, 4.0 and 8.0 individuals mL−1) and diet (Nanno 3600 microalgae paste, Colurella adriatica, Rhodomonas lens, Tisochrysis lutea, Chaetoceros gracilis and/or Tetraselmis chuii) on nauplii production during a single life cycle of reproducing individuals were examined. Results of those trials indicated that a culture temperature of 30°C and a salinity of 30 g L−1 were advantageous for maximum nauplii production. Furthermore, a diet containing a 1:1:1 mixture of T. lutea, C. gracilis and T. chuii and a stocking density of at least 8 individuals mL−1 were identified as beneficial. The results of these trials, the potential for large-scale culture and observations on the performance of marine fish larvae fed Oithona colcarva nauplii are discussed. [ABSTRACT FROM AUTHOR]

This study compared the growth of sea urchin Paracentrotus lividus larvae cultured using two different rearing methods: a variable method based on a variable amount of feed (microalgae) and seawater exchange (30% or 50%) established according to the phytoplankton concentration in the larval cultures and a fixed method characterized by a fixed amount of feed and seawater exchange. Three microalgae diets, Isochrysis sp. (Tahitian strain, T-Iso), Chaetoceros gracilis and a 50:50 mixed diet, were tested with both rearing methods. Larval development and survival were assessed at the 6-arm pluteus stage (P6), competence (Cp) and metamorphosis (Mt). Data showed that the variable method reduced the requirements for phytoplankton and seawater exchange. Indeed, through the optimization of feed rations, it was possible to reduce the production of debris and settled phytoplankton, minimizing the need for water exchanges. Higher larval survival resulted at Cp and Mt stages for those reared with the variable method as opposed to the fixed one. Survival and development were also influenced by the tested dietary treatments: at Mt stage, the mixed diet resulted in a higher larval survival (63.3 ± 8.9%) than T-Iso (19.7 ± 12.1%) and C. gracilis (23.4 ± 15.1%) ( P < 0.05). These results suggest that the use of the variable method improves the larval survival and development and also it reduces resource consumption (phytoplankton, seawater use and work effort), which in turn could potentially improve the hatchery production of P. lividus. [ABSTRACT FROM AUTHOR]

We examined short-term, inter- and intra-individual variability in rates of growth and food consumption in fish early life stages to gain a mechanistic understanding of why larvae in the same environments often grow at vastly different rates. We made parallel measurements of growth rate in standard length ( GRSL) and food consumption rate (C), and provide estimates of weight growth rate ( GRDW) and gross growth efficiency ( GGE = 100* GRDW/C) of individually reared larvae of pikeperch, Sander lucioperca L., fed Artemia nauplii at 20°C and a salinity of 2.0 g L−1. Within two trials, GRSL, C and GGE were obtained for 108 larvae over a maximum period of 28 days. Mean (± SD) initial size, GRSL, C and GGE were 19.49 (9.19) mm, 0.68 (0.21) mm day−1, 0.85 (0.44) mg day−1 and 36.5 (10.2)% respectively. The vast majority (91%) of the variability in growth was explained by differences in food consumption. When isolated from conspecifics for 28 days, relatively small larvae grew faster than relatively large ones, partially mitigating initial differences in size-at-age. [ABSTRACT FROM AUTHOR]

This study describes the effects of feeding taurine-supplemented Artemia on the growth, survival, whole body taurine content and jaw malformation rate of larval yellowtail kingfish Seriola lalandi. Larvae were fed rotifers containing no supplemental taurine from 3 to 15 day post hatch (dph) and Artemia co-enriched with taurine from 12 to 22 dph. Artemia were supplemented at concentrations of either 0, 0.8, 1.6, 2.4, 3.2 or 4.0 g of taurine L−1 during the 18 h HUFA enrichment process. Taurine content in the Artemia increased from 0.76 ± 0.04% DW in those without supplementation to 3.95 ± 0.17% DW in those supplemented at 4.0 g L−1. Survival rates of larval yellowtail kingfish were significantly lower in all taurine-supplemented treatments compared to the unsupplemented control. Growth was significantly improved in those larvae fed taurine-supplemented Artemia; however, we cannot attribute this improvement solely to taurine, as improved growth may have been a function of the reduced survival, and therefore increased prey availability, in these treatments. The whole body taurine content of larvae fed unsupplemented Artemia was significantly lower (1.85 ± 0.03% DW) than those fed supplemented Artemia, which did not differ from each other (pooled average 2.48 ± 0.03% DW), suggesting either a functional excretion mechanism is in place or that this represents the saturation value for larvae of this age. Jaw malformation rates were not affected by Artemia taurine content. The results of this research suggest yellowtail kingfish larvae may have a lower requirement and/or a reduced tolerance to excess dietary taurine than juveniles. [ABSTRACT FROM AUTHOR]

Coral reef fish are collected from the wild and exhibited in aquaria worldwide. Some of the fish spawn in captivity; however, the eggs are usually neglected. In this study, we collected the eggs spawned naturally in the exhibit tanks, hatched and cultured them indoor in 2000-L fibreglass tanks (initial density = 18 000 egg tank−1). We applied an inorganic fertilization method commonly used in freshwater fish culture in raising these coral reef fish larvae. We maintained inorganic phosphorus concentration at 100 μg P L−1 and inorganic nitrogen at 700 μg N L−1 daily in the fertilized group ( n = 4), while the control tanks ( n = 4) were fed with rotifers (10 ind mL−1). Chlorophyll a at particle sizes of both 0.45-20 μm and >20 μm, as well as NH3-N, NO3-N, and PO4-P concentrations were significantly higher in the fertilized group than the control. Zooplankton in the size groups of 10-50 μm (mainly flagellates) and 50-100 μm (mainly ciliates) were abundant (about 10~60 ind mL−1) during 3-7 days in fertilized tanks. The average larval fish survival rate at 21 day after hatch in fertilized group was consistently higher than the control in two trials. The experiments demonstrated that the inorganic fertilization approach can be successfully adapted for coral reef fish culture in an aquarium to achieve sustainable exhibits. [ABSTRACT FROM AUTHOR]

The Bluebanded goby, Lythrypnus dalli, is a popular ornamental aquarium species and a key organism for the study of several fundamental biological questions, most notably reversible sex change in adults. To maximize the tractability of this species as an emerging model system, it is essential to have an optimized propagation system and a detailed developmental staging scheme. One limitation to the larviculture of L. dalli is the relatively small size of the larvae, which makes the transition from yolk to feeding challenging. We developed a protocol and successfully reared three generations of L. dalli in the laboratory. The protocol contains several key innovations for the rearing of diminutive fish larvae, including tank design and co-culturing of microalgae ( Isochrysis galbana) with copepods ( Parvocalanus sp. ) in the larval rearing tanks. In addition, we describe the embryonic and larval development of L. dalli under controlled conditions and in comparison with the model organism Danio rerio. We found that at 21°C L. dalli larvae hatch in 4 days, reach flexion in 18-25 days and are sexually mature by 3 months. Overall, the embryonic development of L. dalli is remarkably similar to D. rerio with several striking differences, including the position and shape of the blastomere, size of the neuromasts and corresponding cupula, and relative timing of pigmentation and brain subdivision. The ability to rear this species in captivity is a valuable tool that could be utilized for a variety of similarly diminutive species and to address a greater breadth and depth of biological questions. [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]

The article focuses on the egg production and growth of copepod Pseudodiaptomus australiensis. Topics mentioned include the species diversity, the effect of temperature on the development of Pseudodiaptomus australiensis, the rate of copepod egg production, and the temperature measurement. Also mentioned are the copepod spawning and the effects of salinity on copepod egg production.

We investigated the first-feeding success of two species: southern bluefin tuna ( Thunnus maccoyii) and yellowtail kingfish ( Seriola lalandi) to determine if similar culture parameters can be used for both, especially when S. lalandi are held in the same tanks as prey for T. maccoyii. The feeding performance (proportion and intensity) was examined in three short-duration (4 h) experiments: prey density, prey size and larval density. Increasing prey density from 0.5 to 25 rotifers mL−1 increased the proportion of T. maccoyii and S. lalandi larvae feeding. Prey size alone did not affect feeding in either species. Seriola lalandi had a decreased proportion of larvae feeding when larval density reached 50 larvae L−1 concurrent with a gradual increase in feeding intensity between 2 and 50 larvae L−1. In T. maccoyii, there was no pattern to the effect of larval density on the proportion of larvae feeding. The overall feeding performance of larvae was higher in T. maccoyii than S. lalandi. Increased prey density improved the first-feeding ability of T. maccoyii and S. lalandi larvae. The effect of larval density on S. lalandi feeding requires further investigation, to ensure that they remain feeding when provided as prey in T. maccoyii culture. The identification of factors in this study, which increase first-feeding success, will improve the culture of both species. [ABSTRACT FROM AUTHOR]

The aim of this study was to report the first successful results on larval rearing of Chaetodontoplus septentrionalis, a description of larval and juvenile development stages, and appropriate first-feed items for pilot-scale larviculture systems. Fertilized eggs were obtained from natural spawnings from communally reared captive wild broodstock. Newly hatched larvae were 2.11 ± 0.06 mm (mean ± SD) in total length ( LT) with 27-28 myomeres. Larvae completed yolk absorption within 3 days post hatching (dph) at 2.92 ± 0.11 mm LT. Transformation of larvae to the juvenile stage was completed at 16.51 mm LT, all fins had the adult complement of rays and spines. A statistical model: Y = ( X × 0.0112) + ( X2 × 0.0086) − ( X3 × 0.00004) + 2.8065, where Y is mean LT (mm) and X represents dph, explained 99.8% of variation in growth ( P < 0.001, R2 = 0.998). The effects of live feed on survival was significantly ( P < 0.05) higher in larvae fed a combination of diet (ciliates, rotifers and copepods) than the others. These results indicate that C. septentrionalis is a potential species for captive breeding programs and the use of a combination of diet may be a suitable first food for the larviculture. [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]

Poor swimbladder inflation leads to low fish survival due to resulting spinal deformities and the inability to feed and develop normally. Failure of swimbladder inflation may be attributed to the inappropriate range of abiotic conditions. This study investigated the effects of temperature, light source and intensity, and oxygen conditions on initial swimbladder inflation, growth and survival of yellowtail kingfish Seriola lalandi larvae. The study consisted of four separate trials including low (21.5°C) and high (24.5°C) temperatures, natural and artificial light sources, low (1000 lux) and high (32 000 lux) light intensities, and ambient and supersaturated dissolved oxygen. Initial swimbladder inflation was only significantly affected by light source, with the highest inflation rate (97.5 ± 3.5%) under artificial light. Fish growth was improved at the higher temperature and at the higher light intensity. Survival was only significantly influenced by light intensity, with the highest survival (11.0 ± 2.3%) at the high intensity (32 000 lux). This study indicates that light source affects swimbladder inflation timing and high artificial light intensity improves larval fish growth and survival. [ABSTRACT FROM AUTHOR]

One of the major challenges in marine fish culture is how to provide live food of adequate size and nutritional quality for first-feeding larvae. Commonly used live food organisms, rotifers and brine shrimp, may not always be the best option. To determine the suitability of different zooplankton in the larviculture of Elacatinus figaro, three diets were tested: RE - rotifers Brachionus sp. (10 ind mL−1)+ciliate Euplotes sp. (10 ind mL−1), enriched with fatty acids; RC - enriched rotifers (10 ind mL−1)+wild copepod nauplii (10 ind mL−1); and R - enriched rotifers (20 ind mL−1). Survival rates were estimated 10 days after hatch (DAH) for the three test groups, and growth rates were evaluated for RE and R at 10 and 20 DAH. Although survival rate was numerically higher for the RC diet (41.1±14.2%), no significant difference was detected between groups fed RE (20.5±18.1%), RC or R (32.1±16.5%). At 10 DAH, the growth rate was significantly higher in RC (5.7±0.6 mm) than in R (4.6±0.5 mm), a trend that was also observed at 20 DAH for RC (8.6±0.5 mm) and R (5.8±0.7 mm) ( P<0.05). E. figaro larvae fed on ciliates did not show satisfactory results, whereas feeding copepod nauplii enhanced growth. [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]

Three candidate probiotics, Bacillus foraminis, Bacillus cereus biovar toyoi and Bacillus fusiformis, were isolated from hydrogen-producing fermented solution and identified using 16S rRNA sequence analysis. Bacillus foraminis and B. cereus biovar toyoi exhibited strong antagonism against Streptococcus iniae and Photobacterium damselae subsp. piscicida in in vitro co-culture for competitive exclusion assay and then were conducted in the larviculture system of Penaeus monodon reared from zoea 1 to postlarva 1. The daily addition of B. cereus biovar toyoi resulted in significantly deleterious effects on survival ( P<0.01) whereas the daily addition of B. fusiformis showed highest survival rate (88.7±0.7%) but no statistically significant difference from control (73.3±12.1%). Bacillus fusiformis was continuously applied in the larviculture system of Litopenaeus vannamei. Administration of B. fusiformis significantly increased survival ( P<0.01) in both treatments added daily (87.9±1.7%) and every other day (54.7±1.2%), respectively, at a concentration of 105 CFU mL−1 over control (41.2±1.3%). [ABSTRACT FROM AUTHOR]

The article discusses the techniques of rearing the glass eels from eggs in Japan. It describes a new rearing system for eel leptocephalus larvae using the planktonkreisel tank which is originally developed for the maintenance of planktonic animals. It is stated that the planktonkreisel system allows the eel growers to raise eels with much lower time and labor costs. It is added that the system could be used to prevent the unfavorable jaw deformity which could have adverse effect on the subsequent survival of glass eels.

The article cites a study in which researchers evaluated the influence of photoperiod on survival and growth of marine pejerrey larvae. They collected fertilized eggs of pejerreywere at Cassino Beach, whose larvae were distributed in 12 larviculture tanks. The researchers tested four photoperiod regimens 0L:24D, 12L:12D, 18L:6D and 24L:0D for 21 days. A registering process of water salinity, temperature and the number of dead larvae in the morning of every study day was implemented. The researchers found that larval survival was not significantly affected by photoperiod. At the end of the ressearch, the larvae kept in the dark were significantly smaller than those reared in the presence of light.

We evaluated the effects of enriched rotifers on growth, survival and on the lipid composition of haddock larvae. The treatments tested were (1) AlgaMac 2000®, (2) AquaGrow® Advantage and (3) Pavlova sp. paste and AlgaMac 2000®. The treatments did not influence larval growth rate throughout the experimental period ( P = 0.70). Larvae from all treatments grew approximately 8% of their dry weight per day between 1 and 29 days post hatch (dph). Treatment 3 resulted in the best survival, estimated to be 3 on a scale from 0 to 5, whereas for the two other groups the survival estimates were 0 and 2. Rotifers from treatment 1 had low sterol concentrations, high eicosapentaenoic acid/arachidonic acid ratio and their feeding resulted in high larval mortality. Rotifers enriched with Pavlova sp. had the lowest proportions of the sum of saturated fatty acids, docosahexaenoic acid and sum of ω3 and the highest proportions of the sum of monounsaturated fatty acids (ΣMUFA). This was partially reflected in larvae from treatment 3 in that they had the highest proportions of ΣMUFA and the lowest proportions of Σω3 ( P < 0.0001 for both analyses). In addition, these larvae had the highest and lowest ΣC20 and ΣC22 polyunsaturated fatty acids (PUFA) respectively ( P < 0.0001 for both analyses). We suggest that more research with ω3 and ω6 PUFA can lead to improvements in the rearing of haddock larvae produced in hatcheries. [ABSTRACT FROM AUTHOR]

Disease problems have emerged as major constraints in aquaculture production. The prophylactic application of antibiotics is expensive and detrimental, i.e. selection of bacteria that are drug-resistant or more virulent and the prevalence of drug residues in reared animals. Probiotics, which compete with bacterial pathogens for nutrients and/or inhibit the growth of pathogens, could be a valid alternative to the prophylactic application of chemicals. A mixture of specific Bacillus strains was designed following a research programme on the ability of numerous Bacillus strains to inhibit a range of pathogenic Vibrio strains, to grow under conditions prevailing in shrimp hatcheries and to degrade waste products. These strains were then included in bioassays and challenge tests in order to confirm the lack of toxin production and pathogenicity to humans, target organisms and the environment. Here, we report on the performance of a commercially available mixture of Bacillus strains (SANOLIFE® MIC), using data from Asian and Latin-American hatcheries, with Penaeus monodon (Fabricius 1798) and Litopenaeus vannamei (Boone 1931). These results show that probiotics may be a suitable alternative to the prophylactic use of antibiotics. Obviously, minimizing the risk of vibriosis demands a multi-disciplinary approach, including good hygiene and sanitation measures to reduce the input of potential pathogens, as well as a suitable farm management. [ABSTRACT FROM AUTHOR]

Common dentex larvae were reared using two culturing techniques, mesocosms and intensive rearing, to determine the principal culture parameters involved in the differences observed in growth, skeletal deformations and survival between the two rearing techniques. In growth, only dry weight of larvae of 40 days post-hatching (dph) from mesocosms was significantly higher than larvae from intensive rearing. Significant differences were observed in survival at 40 dph (6.58% in mesocosms and 1.58% in intensive rearing) and in the incidence of skeletal deformations, both for percentage of deformed larvae and for some deformation types such as those related to vertebral column and to the caudal complex. Initial larval density and initial prey density and quality are the factors suspected to affect growth and survival performance, while skeletal deformities might also be affected by tank hydrodynamics. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to evaluate the effect of rotifers ( Brachionus plicatilis) and Artemia sp. enriched differently on early growth, survival and lipid class composition of Atlantic cod larvae ( Gadus morhua). Rotifers enrichments tested were: (1) AlgaMac 2000®, (2) AquaGrow® Advantage and (3) a combination of Pavlova sp. paste and AlgaMac 2000®. The same treatments were tested with Artemia as well as a combination of DC DHA Selco® and AlgaMac 2000® as a fourth treatment. After rotifer feeding, the larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw)] were significantly heavier than larvae from treatment 2 (1.03 ± 0.04 mg dw). After feeding Artemia, the larvae from treatment 1 were significantly heavier (12.06 ± 2.54 mg dw) than those from treatments 3 (6.5 ± 0.73 mg dw) and 4 (5.31 ± 1.01 mg dw). Treatment 3 resulted in the best survival through the 59 days of larviculture. After rotifer feeding, high larval concentrations of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid (AA) and ω6 docosapentaenoic acid (ω6DPA) could be linked to better larval growth and survival while after feeding Artemia, high larval DHA/EPA ratios (∼3) and high DPA/AA ratios (>1) could be linked to better survival. [ABSTRACT FROM AUTHOR]

We evaluated the effect of differently enriched rotifers on the early growth, survival and lipid composition of Atlantic cod larvae ( Gadus morhua). The enrichments tested were: (i) AlgaMac 2000®; (ii) AquaGrow® Advantage; and (iii) a combination of Pavlova sp. paste and AlgaMac 2000®. Larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw) and 7.10 ± 0.14 dw specific growth rate (SGR)] were heavier ( P = 0.006) and grew faster ( P = 0.004) than larvae from treatment 2 (1.03 ± 0.04 mg dw and 6.29 ± 0.04 dw SGR). No significant differences were found in the final weight and SGR among larvae from treatment 1 (1.21 ± 0.07 mg dw and 6.58 ± 0.20 dw SGR) and larvae from treatments 2 and 3. The treatment 3 also resulted in the best survival at the end of the experimental period, estimated to be 3 on a scale from 1 to 5, whereas the survival estimates for the two other groups were 1–2. Larvae from the treatment 3 reached 37 days posthatch with levels of ω6DPA 32-fold higher than newly hatched larvae. Differences in the larval enrichment of ω6DPA may explain the differences in growth and survival of the Atlantic cod larvae. [ABSTRACT FROM AUTHOR]

Penaeus monodon postlarvae were fed with different percentages (0%, 25%, 50%, 75% and 100%) of the herbal appetizer Zingiber officinalis enriched Artemia. After 30 days of culture (i.e. PL-1–30), a very positive result was found in Z. officinalis-enriched Artemia-fed postlarvae. The unenriched Artemia-fed postlarvae consumed 91.0 mg/animal/30 days of feed, whereas the Z. officinalis-enriched Artemia increased their consumption to 127.9 mg/animal/30 days. A similar pattern was noticed in feed absorbed (110.2 mg), dry weight growth (26.7 mg) and feed catabolized (83.2 mg) in Z. officinalis-enriched Artemia because of enzymatic activities. The conversion efficiency of unenriched postlarva was 17.19%, whereas in 100% Z. officinalis-enriched Artemia, the maximum conversion efficiency was 20.85%. The net production efficiency increased significantly ( P < 0.05) to 22% from that of the unenriched Artemia-fed postlarvae. The administration of Z. officinalis in all levels produced significantly ( P < 0.05) higher weight gain and specific growth rate. The utilization efficiency of feed increased proportionately to the percentages of Z. officinalis. Digestive enzyme activity (amylase, protease and lipase) increased significantly ( P < 0.05) in the 50%, 75% and 100% enrichment. Among the different percentages of enrichment, the 100% Z. officinalis-enriched Artemia-fed postlarvae performed better in the overall status. [ABSTRACT FROM AUTHOR]

This study was conducted with cysts of Streptocephalus proboscideus obtained from the University of Gent-Belgium. The cysts were hatched in Environmental Protection Agency (EPA) medium. The nauplii were reared at the Sturgeon Research Institute using a pure culture of Scenedesmus obliquus alga supplied at a density of 5 × 103 cell mL−1 that gradually increased to 1 × 104, 5 × 104 and 1 × 105 cell mL−1 with the growth of the nauplii. The nauplii attained sexual maturity and started producing cysts in 8 days and yielded a mean cyst number of 220±40 female−1 brood−1 cysts. These cysts were used in the larviculture of Persian sturgeon, Acipenser persicus (Borodin). Forty-three larvae of Persian sturgeon (mean weight: 15.4±1.1 mg; mean length: 27.1±2.7 mm) with roughly absorbed yolk sacs were stocked in three aquaria and fed S. proboscideus nauplii at 8-h intervals. By the end of the experiment (day 5), the mean weight and length of Persian sturgeon larvae were 51.4±13.3 mg and 20.7±1.4 mm respectively. [ABSTRACT FROM AUTHOR]

During culture of grouper, cannibalism is a frequent phenomenon that usually causes economic loss. Grouper culture often requires grading to prevent size-dependent cannibalism. In comparison with orange-spotted ( Epinephelus coioides) and giant grouper ( E. lanceolatus), failure to swallow prey during cannibalism is frequently observed in brown-marbled grouper ( E. fuscoguttatus). The cannibal cannot engulf the entire prey and the two fish ultimately end up dying together. Herein, we attempted to compare morphometric differences among orange-spotted, giant and brown-marbled grouper. We established a cannibal–prey total length (TL) relationship for brown-marbled grouper: TLprey=0.71 TLcannibal−1.75. According to the equation, a difference of approximately 50% in TL is a threshold to use for grading the grouper. This value is much larger than that used (30%) in orange-spotted and giant grouper, and this size difference results in a higher incidence of failed cannibalism attempts in brown-marbled grouper. It is our belief that the standard grading method will fail to produce as good an effect in brown-marbled grouper as is seen in orange-spotted and giant grouper. Therefore, in addition to grading, other manipulations such as satiation feeding, nutritional supplementation and optimal stocking densities should be applied to reduce cannibalism of brown-marbled grouper. [ABSTRACT FROM AUTHOR]

The free-living soil nematode Panagrellus redivivus is well known to be an excellent food source for first feeding fish larvae. It represents an alternative to the highly expensive Artemia, which is commonly used. The lack of a proper method for mass production of P. redivivus has prevented its wider use in commercial hatcheries. A new cultivation method allows the production of a sufficient quantity of nematodes to deliver a standardized and permanently available live food of high quality, throughout the larval rearing period. In two experiments – carried out at the Centro de Investigación en Alimentación y Desarrollo, Mexico – several feeding regimes were established to prove the quality of the mass produced P. redivivus for larvae of Litopenaeus vannamei, the Pacific white shrimp. Two different nematode treatments were compared with a no-feed group and a control group that was fed with Artemia. All treatments had an additional algal co-feed and were run in five replicates. Panagrellus redivivus was cultured on two different media (wheat/corn flour and oat flour) to compare these for their suitability as high-quality live food for the larvae. Shrimp fed nematodes grown on wheat/corn medium reached the postlarval stage earlier than those from other treatments. The nematode treatments showed promising results; however, further research is needed on the development of improved culture media or enrichment methods to further increase the nutritional value of P. redivivus. [ABSTRACT FROM AUTHOR]