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The effect of stocking density on the growth performance, cannibalism and survival of Asian seabass Lates calcarifer fry in the static water system (SWS), and recirculating aquaculture system (RAS) was investigated. Three stocking densities 0.03, 0.04 and 0.05 ind/L were used, where the initial length and weight of the fry were 2.5 ± 0.0 cm and 0.27 ± 0.0 g respectively. At the end of the trial, no significant effect of stocking density was observed on the growth performance of Asian seabass fry (p > 0.05). After 45 days, the total body length and wet body weight were 11.63±0.18cm and 20.06 ± 0.98 g respectively obtained from the RAS were significantly higher than the SWS (p < 0.001). The maximum weight gain (WG) and specific growth rate (SGR) were 19.79 ± 0.98 g and 9.56 ± 0.10% day−1 respectively were found in the RAS significantly higher than the results obtained in the SWS (p < 0.001). A considerably lower FCR (0.67±0.03) in RAS indicated better feed utilization by fish than SWS (p < 0.01). In the present study, cannibalism was highly influenced by the stocking density and culture system and positively correlated with the stocking density. Lower cannibalism was observed at 0.03 ind/L stocking density (27.78 ± 5.56%), and the cannibalism was (35.97 ± 6.28%) in the RAS. There was no natural mortality occurred during the experimental period. The present study suggests that Asian seabass fry reared in the RAS with a lower stocking density can significantly reduce cannibalism and increase the survival rate with better growth performance. [ABSTRACT FROM AUTHOR]

Aquaculture's success highly depends on a controlled rapid growth of organisms with minimal costs associated. Growth and welfare of reared organisms are affected by physical, chemical, and biological parameters. Following factors can be highlighted as crucial: density, pH, salinity, temperature, dissolved oxygen (DO), and nutrients (nitrogen, phosphorus, etc.). Relationship between fish density and oxygen's optimum levels is essential for designing the performance of each species. Furthermore, it is also necessary to study fish stress factors and physiological responses. Two rearing experiments with gilthead seabream (Sparus aurata) were performed, in order to test different densities (5, 10 and 20 kg/m3) for 9 weeks (271 ± 1.9 g) and to test different levels of oxygen (40%–60%, 60%–80%, and 80%–100%) for 6 weeks (316.3 ± 1.73 g). In both experiments, physiology and growth parameters were analysed, as well as water quality. This study showed that no relation was observed between density and fish physiology, but there structural (gill lesions) and physiological changes (haematocrit) were observed for seabream reared at low levels of DO. [ABSTRACT FROM AUTHOR]

Growth parameters of whiteleg shrimp Litopenaeus vannamei and red seaweed Gracilaria corticata were measured using integrated culturing method under zero-water exchange system in a 45-day period. A 2 × 3 factorial design was used with two levels of shrimp stocking densities and three levels of seaweed weight densities. G. corticata was cultured on a net tied to a round polyethylene frame. Culture tanks were filled with 750-L filtered seawater. A 40-W compact fluorescent lamp was hung over each tank to provide adequate and sufficient light for seaweed growth. Growth parameters of shrimp and seaweed such as specific growth rate ( SGR), weight gained ( WG) and average daily growth (ADG) were computed based on the initial and final weight of shrimp and seaweed. The maximum and minimum SGR of L. vannamei (1.97 and 1.69%/day) were observed in treatment S1A3 (25 shrimp/m2 and 400 g seaweed/m2) and S2A1 (50 shrimp/m2 without seaweed) respectively. The best survival rate (94.67 ± 1.33%), WG (129.9 ± 2.9%) and feed conversion ratio (1.67 ± 0.04) were also observed in treatment S1A3. The SGR of G.corticata in the treatment S1A3 (1.97 ± 0.00%/day) was significantly higher, compared to others. Strong positive correlations were obtained between the density of G. corticata and the growth parameters of L. vannamei. The red seaweed G. corticata could boost the growth parameters, survival rate and total production of L. vannamei under zero-water exchange system. [ABSTRACT FROM AUTHOR]

The effect of varying oxygen saturation regimes on growth and haematological profiles of peled Coregonus peled was investigated on fish of initial age 90 days post hatching. Eighty-five juveniles per group (initial body weight 3.09 ± 0.80 g) were submitted to a 63-day experiment with one of four water saturation regimes: normoxia ( NORm, 80%-90%), hypoxia ( HYPo, 50%-60%), hyperoxia ( HYPe, 150%-160%) and intermittent hyperoxia ( iHYPe, 150%-160% - 80%-90%). Survival rate in NORm, HYPe and iHYPe ranged from 96.3 ± 2.1% to 97.7 ± 2.7, but survival 87.5 ± 3.0 was significantly lower in the HYPo group. No differences were observed in feed conversion ratio. The highest final body weight of 18.2 ± 4.6 g and a specific growth rate of 2.81 ± 0.01%/day were seen in the NORm group. Significant differences were found in haemoglobin concentration with increased saturation. The fish had lower haemoglobin 55.00 ± 5.72 and 51.35 ± 10.89 g/L in treatments HYPe, iHYPe with compared to the normoxia (64.22 ± 5.78 g/L). Haematocrit was similar in the groups HYPo, NORm and iHYPe (0.55 ± 0.04, 0.58 ± 0.05 and 0.54 ± 0.09) with the exception of HYPe, which was significantly lower (0.48 ± 0.06). Significantly lower count of erythrocyte was observed in iHYPe group (0.88 ± 0.20) with compared to the normoxia (1.06 ± 0.13). The supersaturation level was not associated with effects on growth and survival, and adding oxygen is not recommended for intensive rearing of peled. The results showed normoxia oxygen level to be the most suitable conditions for peled. [ABSTRACT FROM AUTHOR]

A feeding trial with Macrobrachium rosenbergii was carried out to test the effectiveness of sunflower cake ( SFC) as a replacement for conventional protein sources. Four isonitrogenous (~30% crude protein) and isocaloric (388-402 kcal) diets were formulated. Diet-1 was a control made with conventional ingredients including fish meal, soya bean meal and mustard oil cake. Diet-2, Diet-3 and Diet-4 were made with 30%, 40% and 50% SFC, respectively, replacing the usual protein sources used in Diet-1. After 100 days, diets with SFC inclusion showed favourable growth and economic performance trends compared to control diet-1, but without significant differences ( p > .05). Better production (572.89 ± 62.99 kg/ha) was observed with Diet-4 followed by Diet-2, Diet-3 and Diet-1. Diet-4 revealed the best feed conversion ratio (2.56 ± 0.24), specific growth rate (1.18 ± 0.05) and protein efficiency ratio (1.14 ± 0.10) among these diets. Whole carcass composition analysis revealed highest crude protein (18.19%) and lipid (4.43%) content in prawns fed Diet-3 followed by Diet-4. Highest total income, gross margin and benefit cost ratio ( BCR) per hectare from prawns were US$5,759, US$2,623 and 1.84, respectively, found in Diet-4. This study demonstrates that 30%-50% inclusion of SFC has favourable impacts on productivity and profitability compared with controls, with 50% SFC inclusion as the most cost-effective diet for prawns without apparent compromise in growth, flesh quality or economics. The performances of the diets suggest that SFC may be a suitable substitute for fishmeal, soya bean meal and mustard oil cake in prawn feed. The effectiveness of higher SFC concentrations should also be investigated. [ABSTRACT FROM AUTHOR]

Studies on chronic or acute toxicity of nitrogen species on fish in recirculating aquaculture systems (RAS) usually focused on adverse effects of total ammonia nitrogen (TAN: sum of NH3 + NH4+) and nitrite ( [ABSTRACT FROM AUTHOR]

A 60-day indoor growth trial was conducted to study the effects of biofloc on the growth performance of a Penaeus monodon (Fabricius, 1798), water quality and biological indicators including biofloc volume, chlorophyll- a, heterotrophic bacteria and Bacillus quantity. Two concentrations of sucrose (0 and 75%) were added daily to the P. monodon culture systems (2.94 ± 0.11 g), which were conducted indoors in fibre-glass tanks (500 L). Results showed that the final body weight and weight gain of the adding 75% sucrose group were significantly higher ( P < 0.05) than that of the control, as well as significantly ( P < 0.05) improved specific growth rates and survival rates, and reduced feed coefficient. Adding 75% sucrose promoted heterotrophic bacteria, Bacillus and phytoplankton reproduction, and significantly ( P < 0.05) reduced the concentration of ammonia-N ( NH4-N), nitrite-N ( NO2-N) and nitrate-N ( NO3-N). The changes of water quality indicators in the two groups showed the similar trend at the end of the experiment, and the ammonia-N, nitrite-N, nitrate-N and phosphate-P concentrations in the 75% sucrose group were significantly ( P < 0.05) lower than those of the control group, Chlorophyll- a concentrations peaked at 389.12 μg/L in the biofloc sucrose group at 18:00 h, and heterotrophic bacteria peaked 8 h after sucrose was added. The addition of sucrose also reduced the pH of the water. Our research showed that adding sucrose promoted biofloc formation and shortened the formation time; increased the number of heterotrophic bacteria and algae which might play a role in improving water quality by assimilating ammonia-N and other harmful substances in the water; supplemented food for P monodon growth; and reduced the feed coefficient. [ABSTRACT FROM AUTHOR]

Crowding is one of the most common stressors found in intensive aquaculture, compromising growth rates and immune function. Plasmatic cortisol is a classic stress biomarker for fish, but its quantification is expensive and demands blood volumes that small individuals do not provide, constraining the usage of this technique to assess stress in fingerlings. The leucocyte profile is an alternative methodology to quantify stress with reduced costs and volumes of blood. Stress conditions promote neutrophilia and lymphocytopenia as response to elevated glucocorticoids levels. Considering the difficulties to assess stress imposed by intensive fish farming using measurement of glucocorticoid hormones, this study aimed to evaluate the stress-induced changes in leucocyte profiles and growth rates imposed by crowding in fingerlings of Odontesthes bonariensis, a promising South-American candidate for freshwater aquaculture. To meet these objectives, fingerlings (initial weight 0.05 ± 0.06 g and length 1.68 ± 0.13 cm) were reared for 45 days under three rearing densities (1, 5 and 10 fingerlings L−1). At the end of this period, fish were anaesthetized and euthanized to obtain the leucocyte profile, neutrophil:lymphocyte ratio (N:L) and growth rate. Increasing density promoted: significant reduction in growth (final length, weight and specific growth rate); neutrophilia and lymphocytopenia; and increased N:L ratio. Concluding, the tested rearing densities imposed distinct levels of stress characterized by different N:L ratio, demonstrating that the leucocyte profile is a reliable alternative to measure stress levels in O. bonariensis fingerlings and probably in other fish species. [ABSTRACT FROM AUTHOR]

The nitrate threshold concentration in rearing water of African catfish ( Clarias gariepinus) was assessed. Female African catfish with an initial mean ( SD) weight of 154.3 (7.5) g were exposed to 0.4 (Control), 1.5, 4.2, 9.7 and 27.0 m M nitrate for 42 days. Mean ( SD) plasma concentrations of nitrate increased from 71 (29) to 6623 (921) μ M at the highest ambient nitrate level. Mean ( SD) plasma nitrite concentration ranged from 1.2 (0.5) to 7.9 (9.0) μ M. Haematocrit, plasma concentrations of non-esterified fatty acids ( NEFA), cortisol, glucose, lactate, osmolality, gill morphology and branchial Na+/ K+- ATPase activity were not affected. Feed intake and specific growth rate were significantly reduced at the highest nitrate concentration. We advise not to exceed a water nitrate concentration of 10 m M (140 mg L−1 NO3-N) to prevent the risk of reduced growth and feed intake in African catfish aquaculture. [ABSTRACT FROM AUTHOR]

The article discusses studies of various researchers on "Growth of Domesticated discus Symphysodon sp. at Constant Temperatures." Topics discussed include study of taxonomy of the genus Symphysodon, evolutionary significance in the growth of the aquatic organisms and estimation of optimum temperature for growth. It further discusses the polynomial regression for growth rate of the aquatic organisms.

Based on Box-Behnken experimental design and response surface method, the joint effect of temperature (16-36°C), salinity (0-22 ppt) and rearing density (200-1000 fish.m−3) on the specific growth rate ( SGR) and feed conversion rate ( FCR) of Nile tilapia juveniles were studied under laboratory conditions. The entire experiment lasted for 1 month (30 days). Results showed that the linear and quadratic effects of temperature, salinity on both growth and feed utilization were highly statistically significant ( P < 0.01). The linear and quadratic effect of rearing density on the growth was highly significant ( P < 0.01); the linear effect of rearing density on feed utilization was significant ( P < 0.05), but the quadratic effect nonsignificant ( P > 0.05). Interactions between temperature and salinity, and between salinity and rearing density on the growth statistically differed from zero ( P < 0.05). Interactions between temperature and salinity, between temperature and density on feed utilization was significant ( P < 0.05). Model equations of the growth and feed utilization on temperature, salinity and density were established, with the coefficient of determination being 98.34% for growth and 98.11% for feed utilization, and could be applied to projection. The optimal temperature/salinity/density combination was obtained utilizing statistical optimization approach: 29°C/6 ppt/500 fish.m−3, at which the maximal specific growth and feed utilization reached 4.228%.d−1 and 0.520 respectively, with the desirability being 0.989. [ABSTRACT FROM AUTHOR]

We tested the effects of monochromatic light on the specific growth rate (SGR), feed intake and feed efficiency (FE) of juvenile pikeperch, Sander lucioperca (L.). Pikeperch were reared individually for 42 days in aquaria covered with blue, green, yellow or red gelatin filters or white paper (control; n=5). Linear regression analysis indicated a significant positive effect of longer wavelengths of light on the condition factor (CF), FE and SGR. The final weight, SGR and CF were significantly higher in fish reared under red than under white light, and FE was better under green, yellow and red light than under white light (Dunnett's post hoc test, P<0.05) while blue was comparable to white light in terms of the measured parameters. After the growth trial, the spectral sensitivity of photoreceptor cells in the retina was tested using microspectrophotometry, which revealed the presence of rods with λmax at ca. 530 nm and two cone classes, absorbing maximally at ca. 535 and 603 nm, all containing a porphyropsin-based pigment. These results suggest that the presence of mid and long wavelength-sensitive cones enhances visual sensitivity under mid-wavelength and long-wavelength environments, and thus supports the finding that longer wavelengths of incoming light can improve FE and SGR of the cultivated pikeperch. [ABSTRACT FROM AUTHOR]

The present study was designed to determine the positive effects of artificial illumination on the juvenile black seabream, Acanthopagrus schlegeli, by comparing stomach contents and growth between juveniles exposed to light and those maintained in the absence of light. The major prey items for juvenile black seabream reared in illuminated cages were amphipods (IRI%=50.5), copepods (IRI%=44.7) and polychaetes (IRI%=3.0), whereas those for the juveniles maintained in unilluminated cages were copepods (IRI%=96.0), amphipods (IRI%=3.4) and polychaetes (IRI%=0.6). The specific growth rates (SGR) of the juveniles reared in illuminated cages (0.99%) were significantly higher than those of the juveniles maintained in unilluminated cages (0.78%). [ABSTRACT FROM AUTHOR]