FRP Tanks Research Articles

Understanding the captive breeding, spawning behavior and early ontogeny of Chromis viridis (Cuvier, 1830): A systematic study

The sustainability of aquarium trade relies on successful captive breeding and seed production practices to prevent the long-term consequences of wild collection, which can result in irreversible damage to natural populations. To establish comprehensive breeding and seed production protocols, it is imperative to gain a deep understanding of the reproductive characteristics of the fish, encompassing aspects such as sexual dimorphism, spawning behavior, embryogenesis, and the crucial period of larval survival. Hence, in this study, we document the captive breeding, spawning behavior, embryonic development, and early larval stages of Chromis viridis, a highly sought-after marine ornamental fish that plays a prominent role in the aquarium trade. Fish were sourced from Agatti Island, Lakshadweep, and reared in controlled conditions. Mature fish (6–9 cm) were kept in 500 L FRP tanks with regulated salinity (35.4 ± 0.5 g/L), temperature (27.1 ± 0.54 °C), and a 12-h light-dark photoperiod. After four months in captivity, spawning commenced, characterized by intense substrate cleaning and rapid swimming motions of the male. Each spawning event yielded 3562 to 20,651 eggs. Egg development included five stages over three days at 27.1 ± 0.54 °C, with hatching on the third day. Egg dimensions varied along both axes and egg volume changed over three days. Newly hatched larvae lacked eye pigments and paired fins, with an average total length (TL) of 1.97 ± 0.35 mm. Larval mouth opening occurred at 38 h, and yolk absorption was complete by the third day post-hatch. Continuous captive reproduction was observed with a spawning frequency of 5.59 ± 0.96 days. This study offers valuable insights for standardizing captive propagation techniques and advancing marine ornamental aquaculture for C. viridis by documenting its breeding, embryonic development, and early larval stages in captivity.

Photoperiod manipulation improves growth performance, haematological indices and economic returns of Indian butter catfish, Ompok bimaculatus (Bloch, 1794).

Photoperiod manipulation is emerging as an effective approach for regulating physiological functions in fish. This study aimed to assess the impact of photoperiod on the growth performance, haematological responses, and economic returns of the endangered and highly valued Indian butter catfish, Ompok bimaculatus. Fish with an average body weight of 28.60 ± 4.78g were randomly placed in six FRP tanks, each measuring 120 × 45 × 60 cm3. Each tank contained 20 fish exposed to a light intensity of 1500lx under different photoperiods [24:0 light: dark (L: D), 15L: 9D, 12L: 12D, 9L: 15D, 0L: 24D and a natural photoperiod (control)], and fed at a daily rate of 2% of their body weight twice daily for 60 days. The fish in the 15L: 9D photoperiod exhibited the highest final weight (g), percentage weight gain, specific growth rate (SGR) and survival rate, while the lowest was displayed in 24L: 0D photoperiod group. The feed conversion ratio (FCR) was at its lowest in the catfish subjected to the 15L: 9D photoperiod. Regarding haematological parameters, the 15L: 9D photoperiod group showed higher total erythrocyte count, total leukocyte count, haemoglobin levels, and haematocrit values compared to the other groups. Conversely, the 0L: 24D group, which experienced prolonged darkness, exhibited the lowest values in these parameters. Moreover, the 24L: 0D, 9L: 15D, and 0L: 24D groups displayed a lower mean corpuscular volume (MCV) but higher mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) when compared to the control group. The economic analysis revealed that O. bimaculatus reared in a moderate photoperiod (15L: 9D) displayed better growth, feed utilization, and overall health. This finding suggests that adopting a 15L: 9D photoperiod can lead to enhanced production and improved economic returns for farmers culturing this high-value catfish in the future.

Growth Performance of Critically Endangered Hypselobarbus pulchellus in Biofloc Systems with Various C/N Ratios

Background: Biofloc technology relies on adding a carbon source to maintain optimal carbon to nitrogen ratio for transforming the waste into microbial biomass that aquatic animals can use. In the present study, the growth performance of the critically endangered Hypselobarbus pulchellus in biofloc-based seed rearing with different Carbon to Nitrogen ratio was studied. Methods: Healthy early fry (0.01 g) was randomly stocked into 15 circular FRP tanks (1000 L) at a density of 100 individuals/m3 and reared for 90 days. The carbon to nitrogen ratios of 5:1(CN5), 10:1(CN10), 15:1(CN15) and 20:1(CN20) were maintained using jaggery without considering carbon content derived from the feed and the control group received no additional source of carbon. Result: The results indicated that H. pulchellus had better growth performance in biofloc systems having higher C/N ratios. The highest weight gain (0.48±0.01 g) and weight gain percentage (3931.15±120.68%) and specific growth rate (4.11±0.03% per day) were found in the CN10 group (P less than 0.05), followed by CN15 and CN20, while the control group values were lowest. In terms of survival, all treatments had high survival rates ranging from 92% to 94.67%, with no significant variations (P greater than 0.05). The CN10, CN15 and CN20 treatments had significantly higher amylase, protease and lipase activities than control (P less than 0.05). Moreover, the immunological and antioxidant activity increased with CN ratios. The CN10, CN15 and CN20 groups had significantly lower total ammonia nitrogen, nitrite and nitrate levels than control group (P less than 0.05). Overall, this study suggests that C/N ratios of 10:1 to 20:1 are optimal for rearing H. pulchellus fingerlings from early fry, with 10:1 presenting the best growth results.

Effect of photoperiod on serum biochemistry, electrolytic balance, acute phase response and histopathology of butter catfish, Ompok bimaculatus (Bloch, 1794).

The present study was executed to evaluate the effect of photoperiod on serum biochemical parameters (glucose, cortisol, ALT, AST and LDH), electrolytic balance (Sodium and potassium), acute phase response (CRP) and histopathology (liver, kidney and skin) of an endangered high valued catfish, Ompok bimaculatus. Catfish (21.00 ± 1.53cm and 30.00 ± 2.31g) from the acclimatized stock were randomly distributed to six 120 × 45 × 60 cm3 FRP tanks (n = 20 fish per tank) and exposed to 1500lx light intensity under different photoperiods [24:0 light: dark (L: D), 15L: 9D, 12L: 12D, 9L: 15D, 0L: 24D and a natural photoperiod (control)], and fed at a daily rate of 2% of bodyweight, twice a day for 60days. Serum glucose, cortisol and enzymes including aspartate transaminase (AST), lactate dehydrogenase (LDH), alanine transaminase (ALT), and acute phase reactant, such as C-reactive protein (CRP) increased significantly (P < 0.05) in continuous light (24L: 0D), continuous dark (0L: 24D) and short day (9L: 15D) photoperiods, whereas in 15L: 9D and 12L:12D photoperiods, those were in decreasing trend. Serum electrolytes, i.e. potassium level was elevated and sodium level was declined in 24L: 0D, 0L: 24D and 9L: 15D photoperiod groups. Moreover, significant histological alterations in the liver, kidney and skin tissue were also evidenced in the experimented catfish. Typical polygonal hepatocytes with normal blood vessels in liver and normal organization of kidney were seen in catfish of 15L: 9D group. Histological analysis of other groups displayed nuclear degeneration, karyorrhexis, karyolysis, melanomacrophages, nuclear hypertrophy, sinusoid dilation and vacuolar degeneration in liver and hyaline droplets accumulation, granular degeneration, fragmentation of glomerulus and focal necrosis of epithelial cells in kidney. Additionally, general structure of the skin was observed in control group as well as in 15L: 9D group. Contrarily, in 24L: 0D group increased number of mucous cells and vacuoles was observed in the skin of butter catfish. In 9L: 15D and 0L: 24D photoperiods, O. bimaculatus exhibited ruptured epithelial cells, enlarged alarm cells, fat cells, necrotic cells and vacuoles in the skin tissue. The present study depicted that 15L: 9D photoperiod can induce better health of catfish, O. bimaculatus, which, in turn, can help farmers to increase the production of this high valued catfish in future.

Sugarcane bagasse biochar enhances the growth parameters, haematological parameters, and enzyme activities of genetically improved farmed tilapia (GIFT) reared in inland saline water.

In the present scenario, waste management, especially agro-waste, is one of the major challenges. India is an agrarian country and the economy depends on agriculture and a huge amount of agro-wastes are generated. In this study, biochar was prepared from paddy straw and sugarcane bagasse and was used in the feed of genetically improved farm tilapia (GIFT) at 0.5% (w/w) basis to study its effect on growth and haematological parameters. An experiment was carried out in triplicate in 500-l capacity FRP tanks comprising two treatments and one control. Tanks were filled with inland saline soil to maintain 25-cm soil's bed and water with 12 ppt salinity. A total of 22 fish having an average length of 5.14 ± 0.07cm and weight of 4.8 ± 0.05g were stocked in each tank; the fish were fed at apparent satiation level, twice daily for 45days. It was observed that growth parameters like SGR% (specific growth rate), weight gain (WG%), and feed conversion ratio (FCR) were significantly improved (p < 0.05) than the control. Biochar-enriched feed also significantly improved the haematological parameters like red blood cell (RBC), white blood cell (WBC), haemoglobin (Hb) haematocrit % (HCT), mean cell haemoglobin concentration (MCH), and MCV (mean cell volume) in treatment groups than the control. Feeding biochar as feed additives was also found to decrease catalase (CAT) and enhanced amylase and lipase activities in treatments as compared to control (p < 0.05). It can be concluded that the application of biochar as a feed additive enhanced the growth and overall health of the fish, and it can enhance fish production. However, biochar from sugarcane bagasse was found to be more effective than the paddy straw biochar in the diet of tilapia (GIFT).

Effect of alpha-ketoglutarate supplementation on growth, antioxidant capacity, gene expression and amino acid profile in Nile tilapia (Oreochromis niloticus) under varying protein diets

Protein is the most expensive component in aquafeed and emphasis is given to reduce dietary protein levels without compromising growth. Alpha ketoglutarate (AKG) promotes protein synthesis in fish and improves growth. The present experiment was conducted to investigate the effect of AKG with different dietary protein levels on growth, nutrient utilisation, antioxidant status and immunity in Nile tilapia (Oreochromis niloticus). Five diets were prepared with different levels of protein such as 20 (P20A), 25 (P25A), 30 (P30A) and 35 % (P35A) with 1 % AKG and 35 % protein without AKG (P35C). Nile tilapia fingerlings (300) were randomly stocked in fifteen 150 L capacity FRP tanks with 20 fingerlings (9.91 ± 0.06 g) in each. The fish were then fed with experimental diets twice daily for 60 days. The fish fed with P30A had significantly (P < 0.05) higher growth performance and nutrient utilisation. However, there was no significant (P > 0.05) difference in final body weight and weight gain of tilapia fed with P35C and P25Adiets. The feed conversion ratio (FCR) was significantly higher (P < 0.05) in P20A group and other groups showed alike (P > 0.05) FCR value. The whole body protein and lipid contents of final fish were significantly (P < 0.05) higher in P30A and P25A, respectively. The P25A, P30A and P35A showed increased (P < 0.05) activities of superoxide dismutase (SOD) and catalase (CAT). The activity of metabolic enzymes were also higher in higher protein levels with AKG (P30A and P35A). The expression level of growth gene insulin like growth factor 1 (IGF-1) was significantly up-regulated (P < 0.05) in the P30A. In addition, the relative expression levels of the pro-inflammatory factors tumour necrosis factor (TNF-α) were significantly (P < 0.05) lower in P30A, P25A, and P20A. Total amino acid profile of fish was higher in P35C group. In summary, the optimal choice for enhancing growth and health in Nile tilapia appears to be a diet comprising 30 % protein and 1 % AKG. However, diet of 25 % CP with AKG showed equivalent result in terms growth that of 35 % CP level without AKG. Hence, 25 % protein with 1 % AKG can effectively fulfil protein requirement in tilapia.

Study on the Growth of &lt;i&gt;Macrobrachium gangeticum&lt;/i&gt; Juveniles Fed on Different Diets in Tanks with and Without Soil-Base

The efficacy of two formulated feeds (Feed-I &amp; II) compounded with locally available feed ingredients and one commercial feed (Feed-III) was evaluated on the growth of Macrobrachium gangeticum juvenile. The experiments were conducted during January to April 2005 using 1000 l capacity FRP tanks. While one set of tanks was provided with soil-base, the other set was without soil-base. Each tank was stocked with hatchery-produced M. gangeticum seed of 3.8 - 4.8 g (90.6-97.6 mm) at density of 50/m3. Prawns were fed twice daily at 10% of the body weight. Results indicated that units with soil-base exhibited significantly higher (p&lt;0.05) weight gain (113.15% in Feed-I; 40.82% in Feed-II; 66.67% in Feed-III) than without soil-base (70.73% in Feed-I; 37.50% in Feed-II; 42.50% in Feed-III). The performance of Feed-I in terms of weight gain and specific growth rate was the best followed by Feed-III and Feed-II.

Brood Rearing, Induced Spawning and Egg Incubation of Channa Striatus in an Indoor System With a Note to Its Second Breeding in the Same Season

Channa striatus broods were raised in ferro-cement cisterns at stocking density 2.0 kg/m3. GSI (ovary) of above brood was lowest during December (1.0670.157) and highest during June (9.340.331). Matured broods were induced bred with WOVA- FH (a GnRH based inducing agent) in a rectangular FRP tank. The breeding response was recorded as 88% with spawning fecundity 26.871±6.301 x 103 (ranged 17.142 x 103-36.585 x 103) and spawn recovery rate was 20.238± 5.074 x 103 (ranged 14.056 x 103- 30.365 x 103). The spent broods were further reared in the ferro-cement cistern for further study. The GSI of spent brood were enhanced from 5.0130.870 to 8.88± 0.318 within a period of 45 days and the fish could be induced bred for 2nd time after 60 days of initial spawning. The breeding success for 2nd instance was recorded 30% with spawning fecundity of 21.636±4.789 x 103 (ranged 18.71 x 103- 27.16 x 103) and spawn recovery rate of 16.086± 2.56 x 103 (ranged between 14.270 x 103-19.014 x 103). The GSI of spent fish after second breeding was again reduced to 4.8380.442.

Evaluation of Biofloc-Based Probiotic Isolates on Growth Performance and Physiological Responses in Litopenaeus vannamei

A comparison of the growth performance of Penaeus vannamei was ascertained by supplementing the potential probiotics isolated from a biofloc system incorporated through feed. Post-larvae shrimp (0.045 ± 0.005 g) were stocked at a density of 500/m3 in FRP tanks (500 L) in triplicates for a period of 60 days. A total of 40 bacterial strains were isolated from previous biofloc culture trials and tested for their antimicrobial activity against the pathogen Vibrio parahaemolyticus. Among these, Bacillus megaterium, Exiguobacterium profundum, Pseudomonas balearica, and Pseudomonas stutzeri showed higher antimicrobial activity. The treatment groups included clear water with no probiotics (CW), clear water + isolated probiotic (CW + IP), biofloc alone (BFT), and biofloc + isolated probiotic (BFT + IP), in triplicates. Distillery spent wash was used as a carbon source for biofloc development and maintenance. A probiotic concentration of 1 × 109 cfu/g was supplemented throughout the trial. The recorded water quality parameters (pH, alkalinity, calcium, and magnesium) were observed to be significant among the experimental groups (p ≤ 0.05). The highest weight gain (2.43 g), SGR, PER, and lower FCR values were recorded in BFT + IP. The lowest values of total Vibrio were found in BFT. The histology analysis revealed that there was a mild increase in the B and R cell vacuoles in the hepatopancreas of CW and BFT + IP, whereas mild degeneration was found in the intestine of CW and CW + IP. Microbiome analysis of the shrimp gut revealed that Proteobacteria was the most abundant phylum in all experimental groups. P. balearica, K. pneumoniae, P. stutzeri, and E. profundum were present in the gut of C, whereas P. balearica, K. pneumonia, and P. stutzeri were present in the gut of CW + IP and BFT + IP. The results proved that the probiotics isolated from biofloc colonized in shrimp gut could play a promising role in aquaculture.

Effect of Beta vulgaris L. as feed ingredient on muscle growth, nutritional factors, and quality of common carp, Cyprinus carpio.

The purpose of this study was to evaluate the utilization of Beta vulgaris powder as feed ingredient in the diet of Cyprinus carpio for a period of 56 days. Common carp fry with an average weight of 20 ± 0.2 g were fed using the diet containing B. vulgaris leaves with different concentrations. Fry of Cyprinus carpio were equally distributed in four feeding groups having three replicates each. The study was conducted indoors, in FRP tanks, and aeration was provided to individual rearing units, and it was a flow-through system. The basal diet was replaced at 0.5%, 1%, and 2% with B. vulgaris powder. The basal diet without B. vulgaris powder (0%) served as control (T1). Significantly higher feed conversion ratio, protein efficiency ratio, and fat and protein indices were recorded in fish fed with B. vulgaris powder in treatments. Different feeding groups showed greater acceptability of B. vulgaris powder mixed diet without any adverse behavioral response. The protein and fat average percentages were 43.32 and 10.79 g, when fish reached commercial weight (48.02, 11.85 g) after 56 days for treatment 2%. After fish feeding with the B. vulgaris, for treatment 2% lower moisture than the control was recorded. The carp fish diet containing 1% B. vulgaris leaf powder caused a significant decrease in the fish fat content. It can be concluded that the diet containing 2% B. vulgaris leaf powder in the common carp led to better growth performance. The presence of B. vulgaris leaves in the fish diet increased the fillet protein and ash content.

Potassium amendment of inland saline groundwater: Insights into the physiological responses of silver pompano Trachinotus blochii (Lacepede, 1801) at different salinities

A trial was conducted to evaluate the effect of graded levels of potassium (K+) amended inland saline groundwater (ISW) on serum ionic composition, antioxidant and metabolic enzymes [Na+/K+ATPase, Catalase, Superoxide dismutase (SOD), Glutathione peroxidase (GPx), Glutathione S-transferase (GST), Lactate dehydrogenase (LDH), aspartate aminotransferase (AST)] activities of silver pompano, Trachinotus blochii (Lacepede, 1801). The ISW was amended with 100% K+ at 5 ppt (ISW5), 10 ppt (ISW10) and 15 ppt (ISW15) and reconstituted seawater (RSW) with similar salinities (RSW5, RSW10 and RSW15) was employed as a reference medium. Experiment was conducted using completely randomised design. T. blochiijuveniles (1.5±0.5 g) were reared in 300 l capacity circular FRP tanks for 90 days. Fish were fed with commercial extruded floating feed. At the end of experimental period, serum ionic composition, enzymatic profiles and proximate composition were estimated. Results of the study showed that the serum ionic content (K+, Na+, Ca2+ and Mg2+) varied dose-dependently with salinity (p&lt;0.05). Na+/K+ATPase, antioxidant enzymes (Catalase and SOD) and metabolic enzymes (GPx, GST, LDH and AST) showed higher activities at lower salinity (ISW5 and RSW5) compared to fish reared at 10 ppt and 15 ppt ISW. Similarly, proximate composition exhibited significantly (p&lt;0.05) lower protein and lipid content at lower salinity (ISW5 and RSW5) signifying the stress condition at lower salinity. Physiological responses of T. blochii in terms of serum ionic composition, enzymatic profile and proximate composition were optimum at 10 and 15 ppt amended ISW, implying that rearing at 10-15 ppt with 100% K+ amendment of inland saline groundwater is appropriate. Keywords: Antioxidant activity, Inland saline groundwater, Metabolic enzymes, Potassium amendment, Proximate composition

The green seaweed, Enteromorpha intestinalis: An efficient inorganic extractive species for environmental remediation and improved performances of fed species in brackishwater integrated multi-trophic aquaculture (BIMTA) system

Seaweed has vast utilization benefits, in terms of food, cosmetics, fertilizers, and extraction of industrial gums and chemicals. Moreover, in integrated multi-trophic aquaculture (IMTA), seaweed can be utilized as an inorganic extractive species, but a very few studies were conducted so far involving the green seaweed, Enteromorpha sp. An experimental trial of 60 days was executed to ascertain the effect of varied stocking densities of Enteromorpha intestinalis on growth parameters, survival and physiological status of milkfish, Chanos chanos and the Pacific white-leg shrimp, Penaeus vannamei, and bioremediation effect in brackishwater IMTA (BIMTA) systems. There were three BIMTA systems with different biomass densities of seaweed, 0.5 (T1), 1.0 (T2), and 1.5 (T3) kg m−3 placed in 1000 L FRP tanks stocked with C. chanos (3.50 ± 0.01 g) at 25 number m−3 and P. vannamei (4.25 ± 0.04 g) at 50 number m−3 as fed species. The control (polyculture) had same number of milkfish and shrimp with no seaweed. Three treatments and control were maintained in triplicate. The fed species were provided with a polyculture feed containing 30% crude protein at 5% of the biomass daily. The results displayed that nitrogenous and phosphorus compounds were significantly lower (P < 0.05) in all three BIMTA treatments compared to the control. A better growth (P < 0.05) of C. chanos (12.52 ± 0.24 g) and P. vannamei (14.77 ± 0.35 g) was obtained in T3 and T2 BIMTA systems, respectively when compared with the control (milkfish: 11.01 ± 0.08 g, shrimp: 11.79 ± 0.58 g). Survival in shrimp was the highest in T3 treatment, but in milkfish, survival did not vary between different systems (P > 0.05). The blood (red blood cells, white blood cells and haemoglobin) and haemolymph (haemocyanin and total haemocyte count) parameters were better in fish and shrimp, respectively under BIMTA at harvest. Presence of seaweed provided a significant positive effect on the welfare parameter (glucose), whereas stress parameters (catalase, superoxide dismutase and cortisol) were comparatively low in fed species of BIMTA treatments than that of polyculture system. This trial suggested that T2 and T3 performed better among all and E. intestinalis can be an efficient inorganic extractive species for BIMTA at the optimum stocking density of 1.0–1.5 kg m−3.

Effect of Dietary Lysine and Methionine Supplementation on the Growth and Physiological Responses of Pearlspot Fingerlings, Etroplus suratensis

Background: Successful and sustainable culture of finfish and shellfish depends on the use of nutritionally balanced, low-cost and eco-friendly feeds. This experiment was conducted to evaluate the effect of dietary supplementation of lysine and methionine on the growth and physiological responses of juvenile pearlspot, Etroplus suratensis. Methods: Fingerlings with an average initial body weight of 8.7±0.04 g were distributed to the 300 L FRP tank (n=30 pieces/tank). The pearl spot fingerlings were fed with isonitrogenous (25% Crude protein) feeds supplemented with methionine (1.8, 2.2 and 2.6 g/100 g of diet) and lysine (0.5, 0.9 and 1.3 g/100 g of diet). The growth performance and physiological response of the fishes were assessed. The feeding trial was conducted for a period of 60 days. Result: The methionine supplemented diets at 2.2 g/100 g (T2) and Lysine supplemented diet at 0.9 g/100 g (T5) yielded the best results within the treated groups in terms of average body weight gain, FCR (feed conversion ratio), SGR (specific growth rate), PER (protein efficiency ratio) and FER (feed efficiency ratio). The maximum mean body weight gain recorded in methionine supplemented diet was 20.68±0.20 g in T2 and the maximum mean body weight gain recorded in lysine supplemented diet was 19.6±0.15 g in T5. The mean body weight gain in control was recorded as 12.12±0.20 g. The present study revealed that methionine incorporation at 2.2 g/100 g (T2) and lysine incorporation at 0.9 g/100 g (T5) resulted in better growth performance of the pearl spot Etroplus suratensis fingerlings. Results of challenge tests confirmed that V. anguillarum could act as a primary pathogen for pearlspot reared in freshwater. In the present study, the Hb, RBC, MCV, MCH and MCHC were also affected by dietary methionine and lysine supplementation and were found significantly (p less than 0 .05) higher in fish fed methionine at 2.2% and lysine at 0.9% of diet, indicating that dietary methionine and lysine supplementation activates immune response and promotes fish health. Second-order polynomial regression analysis of weight gain against dietary methionine and lysine levels indicated that the optimum dietary methionine and lysine requirement for maximum growth and feed utilization of pearlspot fingerlings was methionine at 2.2% and lysine at 0.9%.

Herbal Feed Additives for Gonadal Maturity and Breeding Performance of Female Snow Trout (Schizothorax richardsonii) in Captive Condition

Addressing the issue of gonadal maturity and breeding in captive condition for a commercially important indigenous Coldwater fish, snow trout, Schizothorax richardsonii, field study was conducted with dietary supplementation of the blend of Ashwagandha (Withania somnifera) root powder, dried powder of garlic (Allium sativum), and hing (Ferula asafoetida). Experimental fish of 3 years age were reared in FRP tanks (n = 4) of 1200 L capacity with stocking density of n = 60 in each tank and fed with control (CD) and experimental (TD) diets in duplicate at the feeding rate of 3–5% of their body weight twice in a day. Gonadosomatic index (GSI) and hepatosomatic index (HSI) were recorded for annual breeding cycle coupled with breeding indices in breeding season and regular monitoring of water quality parameters. In female stock, the GSI values ranges from 0.87 to 12.83 and 1.84 to 15.42 in control and treated groups, respectively. Two peaks of GSI values reflects the two breeding season of the species during the month of March and September. Similarly, HSI was lowest during the month of March and September in captive reared female fish and highest during the month of May to June and January to February, with similar trend in both, control treated and groups. In captive condition, 80% specimens were observed mature for spawning in treated group, while only 15% females were ready to spawn in control stock. The fecundity of the fish was observed in the range of 20210-23710 eggs/kg body weight with 80–94.2% fertilization rate. The egg size was observed in the range of 3.5–3.8 mm. The study revealed that 1.0% supplementation of blend of herbs in the diet is beneficial for gonadal maturity of females and better spawning of S. richardsonii in captive Coldwater condition.

Utilization of Complex Carbon Sources on Biofloc System and Its Influence on the Microbial Composition, Growth, Digestive Enzyme Activity of Pacific White Shrimp, Penaeus vannamei Culture

A two-month experiment was conducted to evaluate the effect of complex carbon sources on the biofloc system and its influence on Penaeus vannamei culture. Four sources of carbon viz. Tapioca flour (BFTf), Rice bran (BFRb), Wheat flour (BFWf), Rice Flour (BFRf), and biofloc were generated, the absence of CHO being considered as control (C). The experiment was carried out in 100L FRP tanks in triplicate, and the post-larvae (ABW: 0.11 g) were stocked @ 400 PL/m3. Results revealed that the addition of complex carbon sources effectively reduces the TAN by 62-67%. The average body weight of shrimp in the rice flour and wheat flour treatments were significantly higher compared to control. Similarly, improved survival was observed in rice bran treatment (89%). Beneficial bacteria were isolated from all the treatments as well as control. Real-time analysis revealed significantly (P&lt;0.05) higher expression of digestive enzyme-related genes compared to control the utilization of carbohydrates, exhibiting an encouraging trend. The complex carbon sources (BFRf) and (BFWf) have been effectively utilized, resulting in improved water quality, microbial diversity, growth performance, and enhanced digestive enzyme activity.

Effect of salinity changes on growth, survival and biochemical parameters of freshwater fish Gibelion catla (Hamilton, 1822)

Aim: The present investigation was conducted to access the effect of salinity stress on growth performance, survival and biochemical parameters of Gibelion catla under different salinity conditions with an idea to assess the potentiality of this species in inland saline affected areas. Methodology: A 30-day-experiment was conducted in 1000 l (n=10) FRP tanks to study the effect of different salinity levels on the growth and biochemical parameters of catla species. A total of 120 fish (10.4 g) was randomly distributed into four treatments (0, 3, 6 and 9 ppt) with three replicates. The water quality parameters such as pH, temperature, nitrite, nitrate, ammonia, alkalinity and dissolved oxygen were recorded for each treatment on weekly basis, whereas fish sampling was carried out at 0th and 30th day of the experimental period to ascertain survival, weight gain, specific growth rate and feed conversion ratio of the fishes from each treatment. Results: The highest growth rate was found in control subsequently in 3 and 6 ppt and the survival rate was 96.67, 83.33, 76.67 and 0% against 0, 3, 6 and 9 ppt, respectively. The red blood cells (3.65×106 μl) and haemoglobin concentration, (8.17 gm dl-1) were also higher in control fish, followed by 3 and 6 ppt. However, white blood cells (24.40×106 μl) and glucose level (123.23 mg dl-1) were higher at 6 ppt, compared to control. Plasma protein level of fish at control (0 ppt salinity) was significantly higher than those of fish exposed to 3 and 6 ppt salinities. Interpretation: The present investigation revealed that an increase in salinity level had a significant impact on the growth and physiology of Gibelion catla. However, this species can be reared in low saline areas for some time which will not only help in the utilization of salt affected areas but will also help in the generation of employment and income.

​Early Weaning of Asian Stinging Catfish, Heteropneustes fossilis (Bloch) Larvae

Background: Heteropneustes fossilis commonly known as stinging catfish is a popular indigenous fish of the Indian sub-continent. The species has a high consumer demand because of its tender flesh, low fat and high iron content, and is recommended for anaemic patients. Although the species has high consumer preference and potential for commercial aquaculture but, high mortality of larvae and difficulties in accepting compound diet during larviculture are some of the major bottlenecks. Keeping this in mind, the present study was designed to determine the earliest age at which stinging catfish can be weaned to an artificial diet. The information generated from the present study would be very helpful in improving survival during larval rearing. Methods: The larvae were randomly distributed @ 60 larvae/ tank in 21 circular FRP tanks containing 30 L water each and the feeding experiment started at 2 dph. Seven different feeding strategies depending on the type of food (zooplankton, Artemia nauplii, or microdiet) and the age at which those food items were provided to larvae, were evaluated. Result: The results indicated that larvae survival in the groups weaned after 5 days post hatch (dph) was similar to that of those fed solely with Artemia nauplii and zooplankton, although growth of larvae in the weaned groups was less. As larval growth can be compensated at later stages of the rearing process, therefore, larval survival is considered as one of the most important parameters for evaluating the weaning success. Based on the present findings, it is suggested to rear stinging catfish larvae with zooplankton without dependence upon costly Artemia nauplii, and larvae may be weaned to artificial diet after 5 dph. The findings would be very helpful for improving larval rearing of this indigenous catfish species in Indian rural areas.

Breeding, larval rearing and growth of black Amphiprion ocellaris (Cuvier, 1830) under captivity

Broodstock development, breeding, spawning, larval rearing and growth of black Amphiprion ocellaris in captivity are described in this study. The black ocellaris, a magnificent colour morph of A. ocellaris was bred in captivity at Vizhinjam Research Centre of ICAR-Central Marine Fisheries Research Institute (ICAR-CMFRI). Two adults, approximately 4-6 cm in total length (TL) were stocked in FRP tanks of 300 l capacity, under optimum water quality. The broodfishes were fed a combination of boiled mussel meat, boiled squid and semimoist feed (protein - 40 %, lipid - 9.5 %, fibre - 2% and moisture - 31%) twice daily at a rate of 3-5% of their body weight. After a period of 1.7 years, the fishes started showing courtship behaviour and initiated spawning. The oocytes were of 3-3.3 mm in length and 1.1-1.9 mm in width. Approximately 200-300 eggs spawned the first time and the number of eggs gradually increased in subsequent spawnings. Spawning was obtained at an interval of 12-14 days providing an average of two spawnings per month. The incubation period of the eggs were 7-8 days and the fertilised eggs hatched on the 8th day, soon after sunset, generally between 19.00 and 20.00 hrs. Different strains of cultured plankton like Isochrysis galbana, Nanochloropsis oculata, L-type rotifer Brachionus plicatilis, calanoid copepod Acartia southwelli and Artemia were used as feed for larvae. The newly hatched larvae with a total length of 5±0.16 mm metamorphosed to juveniles on the 40th day (18.87±0.07 mm). Black ocellaris is a highly priced clownfish and can be used to crossbreed with the normal orange coloured ocellaris clown fish to produce different colour variants. Keywords: Black Amphiprion ocellaris, Breeding, Broodstock development, Larval Rearing, Live feed, Variants

Development of indoor grow‐out practices for polychaete, Marphysa gravelyi with a note on biochemical composition

Polychaetes are multi-segmented worms, being exploited from the backwaters for shrimp hatcheries to be used as a maturation diet for shrimp broodstocks. Non-selective collection of polychaete worms poses a severe hazard to the ecosystem; hence, a grow-out system was developed for Marphysa gravelyi. Adult, M. gravelyi of 17 ± 0.4 cm length (n = 40) when reared in 100 L tanks, produced 1800 numbers of juveniles having an average length of 7 ± 0.2 cm with 80% survival in 4 months. The juveniles (7 ± 0.2 cm (n = 50) worms were reared again in 25 L tubs from which 45 adults (20 ± 0.3 cm) could be produced in 4 months with 90% survival. Juvenile, M. gravelyi (n = 500) when mass-reared in 1000 L FRP tanks by feeding Skeletonema costatum (106​ CFU/ml), produced 400 adults (20 ± 0.2 cm) as biomass with 80% survival in 4 months. The nutrient profile of adult M. gravelyi revealed protein, carbohydrate and lipid to be 33, 14 and 40 g % respectively. Crude M. gravelyi extract showed the highest bacterial inhibition on Staphylococcus aureus (18 ± 0.3 mm) and lowest on Bacillus subtilis (14 ± 0.2 mm). The present study revealed that growing polychaete worms in a controlled condition is advantageous, compared to collection of polychaete worms from wild which might seriously deplete their natural stocks, and cause physical disturbance of soil exposing heavy metals with the release of ammonia, and phosphorus compounds leading to eutrophication.

Effect of different organic manures and salinity levels on greenhouse gas emission and growth of common carp in aquaculture systems

A study was conducted to evaluate the effect of three different organic manures and salinity levels on production of greenhouse gases (GHGs) and their interactive effects on growth and physiological parameters of common carp (Cyprinus carpio) in peri-urban aquaculture tank system. The experiment had 3 × 3 factorial design with three types of organic manures, that is humic acid, FMGY (fermented boiled rice, molasses, groundnut oil cake and yeast) and cow dung tested in combination with three different salinity levels, that is 0.2, 2.5 and 5.0 g/L in triplicates. C. carpio fingerlings (average weight and length of 7 g and 7.15 cm respectively) were distributed to 27 number of 1000-litre FRP tanks (nine treatments with triplicates) containing 10 fish per tank. Fish were maintained for an experimental period of 180 days with a diet containing 30% crude protein. GHG estimation was done on 120th, 150th and 180th days at 30-day interval by collecting gaseous sample following floating chamber method. Lowest GHG emission (917.73) CO2 equivalent (mg m−2 h−1) was recorded in T3 treatment (humic acid + 5 g/L salinity). Highest fish growth was evident in T2 treatment (humic acid with 2.5 g/L salinity). GaSI and HSI were higher in treatment T2. Lowest stress parameters (plasma glucose and serum cortisol) were recorded in T4 treatment (FMGY with 0.2 g/L salinity). In terms of GHG emission, growth and bio-indices in C. carpio tank rearing, humic acid is the best organic manure at less than 5 g/L water salinity.