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Aim: To assess the impact of different carbon sources on growth performance of grey mullet, Mugil cephalus fry in biofloc based culture system during nursery rearing phase. Methodology: The experimental trial was carried out for 60 days using three carbon sources, cassava, jaggery and barley in triplicate following a Completely Randomized Design. The carbon nitrogen ratio (C:N) in the systems were maintained at 15:1. Grey mullet fry (0.91g) were stocked @ of 1 fry 10 l-1 and were fed with pelleted feed (35% crude protein) @ 4% of fish body weight thrice daily. Results: Significantly higher (P

Aim: This study aimed to investigate the effectiveness of ethanolic extract of three Himalayan plants Myrica esculenta, Thymus linearis and Butea monosperma on hyphal germination, colonisation and sporulation of two species of Saprolegnia (Saprolegnia parasitica and S. australis) isolated from rainbow trout, Oncorhynchus mykiss. Molecular docking of active ingredients of M. esculenta, Myricetin with effector proteins of S. parasitica was also performed to investigate the target binding sites for drug development. Methodology: Minimum inhibitory concentration (MIC), mycelium growth inhibition, spore germination, and inhibition was performed with the most effective concentrations. Molecular docking was carried out with AutoDock Vina software to investigate target binding sites with S. parasitica. Results: Extracts from Myrica esculenta, Thymus linearis and Butea monosperma showed MIC values of the 25, 100, 50 mg ml-1 against S. parasitica and 25, 50, 25 mg ml-1 against S. australis hyphal growth, respectively. Nevertheless, malachite green as reference control was effective with a MIC value of 2.5 mg l-1. The concentration required to inhibit S. parasitica and S. australis spores were (50) Myrica esculenta, (25) Thymus linearis, (100) Butea monosperma in mg ml-1 and (50) Myrica esculenta, (50) Thymus linearis, (100) Butea monosperma in mg ml-1, respectively. Interpretation: The study concludes that M. esculenta and B. monosperma are effective against Saprolegniasis and could be used as phyto additives.

Global agriculture is facing tremendous challenges due to climate change. The most predominant amongst these challenges are abiotic and biotic stresses caused by increased incidences of temperature extremes, drought, unseasonal flooding, and pathogens. These threats, mostly due to anthropogenic activities, resulted in severe challenges to crop and livestock production leading to substantial economic losses. It is essential to develop environmentally viable and cost-effective green processes to alleviate these stresses in the crops, livestock, and fisheries. The application of nanomaterials in farming practice to minimize nutrient losses, pest management, and enhance stress resistance capacity is of supreme importance. This paper explores innovative methods for synthesizing nanostructured materials using plants, animals, and fisheries wastes and their valorization to mitigate abiotic and biotic stresses and input use efficiency in climate-smart, and stress-resilient agriculture including crop plants, livestock, and fisheries.

Global agriculture is facing tremendous challenges due to climate change. The most predominant amongst these challenges are abiotic and biotic stresses caused by increased incidences of temperature extremes, drought, unseasonal flooding, and pathogens. These threats, mostly due to anthropogenic activities, resulted in severe challenges to crop and livestock production leading to substantial economic losses. It is essential to develop environmentally viable and cost-effective green processes to alleviate these stresses in the crops, livestock, and fisheries. The application of nanomaterials in farming practice to minimize nutrient losses, pest management, and enhance stress resistance capacity is of supreme importance. This paper explores innovative methods for synthesizing metallic and non-metallic nanoparticles using plants, animals, and fisheries wastes and their valorization to mitigate abiotic and biotic stresses and input use efficiency in climate-smart and stress-resilient agriculture including crop plants, livestock, and fisheries.

An experiment was conducted to study the influence of environmental parameters and stocking density on growth, survival, feed utilization, and economic feasibility of a high value butter catfish, Ompok bimaculatus in floating cages in a large tropical reservoir of India for 180 days. The fingerlings (11.44 ± 1.33 cm; 8.05 ± 3.27 g) were stocked at three stocking densities, viz., 15, 25 and 35 fingerlings m-3 in GI cages (32m3) in triplicates. Commercial floating pellets were fed to fish at 5–3% of fish biomass. The results indicated that the fishes at the lowest stocking density of 15 fingerlings m-3 had significantly higher (p 0.05) between stocking densities of 15 fingerlings m-3 and 25 fingerlings m-3. The condition factor was insignificantly higher at lower densities and its values close to 1 indicated congeniality of reservoir ecosystem for cage culture of the species. The coefficient of variation of weight was significantly higher (24.19 ± 1.20) at 35 fingerlings m-3. The highest economic gains in terms of benefit cost ratio (1.77) were achieved at the lowest stocking density. The present study indicated better growth and economic returns at lower stocking densities of 15–25 fingerlings m-3. The nutrient load and plankton abundance were higher at culture site, however, did not vary significantly from reference sites throughout the culture period. Although most of the environmental parameters showed significant seasonal variations, dissolved oxygen showed significant positive relation (r = 0.86) with the growth of the fish. This is the first study reporting feasibility of cage culture of this highly renumerative species in open waters. The cage culture of this species will not only ensure better economic returns to the marginal cage farmers but will aid in the conservation of this species in natural ecosystem. Being a low volume high value species, the impact on environment will be less compared with high volume low value species. This study will serve as baseline for standardization of its grow-out protocol in cages and will be a step towards much needed species diversification for sustainable small scale cage farming in tropical reservoirs of Asia.

Aim: The objective of the study was to assess the effect of supplementation with dietary shatavari, Asparagous racemosus root extract on growth, feed conversion and nutrient utilization in Labeo rajasthanicus. Methodology: Two-hundred-seventy fingerlings of equal size (8.19±0.03g) were stocked in 18 fibre reinforced plastic tanks following complete randomized design. Six iso-nitrogenous (30% crude protein) and iso-caloric (390 kcal digestible energy per 100 g) diets were prepared with graded level of ethanolic shatavari root extract, i.e., 0.00, 0.15, 0.30, 0.45, 0.60, 0.75 g kg-1 and designated as control, T1, T2, T3, T4 and T5 were fed to L. rajasthanicus twice a day for 45 days. The growth performance, feed conversion and nutrient utilisation were considered as response parameters. Results: Significantly (P

Reproductively mature koi carps (Cyprinus carpio) showed a prominent diurnal variation of sex steroids with sustained nocturnal rise. Exposure to chronic hypoxia (DO

The success of any aquaculture endeavour broadly depends on water quality. Water quality determines to a great extent the success or failure of aquaculture operation. Optimum water quality is considered necessary for any aquaculture operation as it influences the productivity of production system. In the present review, the role of major abiotic factors such as water pH and hardness on the biological processes of fish like growth, survival, reproductive performance and embryology has been discussed.

Background: Stunting is a process of suppressing growth from unfavourable conditions. The protein supplementation during stunting gives scope to maintain the nutrient reserves of fish and its quality. Methods: A feeding trial was conducted for eight months to study the effect of three hetero-nitrogenous diets with 25% (control), 30% (T1) and 35% (T2) crude protein (CP) levels on growth and physio-metabolic responses of Chanos chanos fingerlings during stunting. Milk fish fingerlings with a mean body weight of 11.71±0.18 g were stocked in earthen ponds @ 20 no/m2 in each replicate (n=3) was fed @ 2% biomass throughout the experiment. Result: Fish fed with T1 diet showed better specific growth rate (0.64±0.01% d-1), weight gain percentage (362.56±14.95) and protease activity (7.53±0.25 U/mg protein). Whereas, lower activity was observed for the enzyme assay, namely superoxide dismutase (45.41±2.50 U/min/mg protein), aspartate aminotransferase (34.01±1.88 U/min/mg protein) and alanine aminotransferase (39.64±0.64 U/min/mg protein). Hence, it may be concluded that the dietary protein inclusion level of 30% CP showed better growth performance and lower physio-metabolic response in milkfish fingerlings during the stunting.

The present study was conducted for 240 days to evaluate the effects of stocking density based on growth attributes, digestive enzymes, muscular composition, biochemical and physiological responses of Labeo rohita fingerlings in tropical inland open water cages. L. rohita (30.35±1.08 g) were randomly distributed into three treatments, namely low stocking density, LSD (10 m− 3), medium stocking density, MSD (20 m− 3) and high stocking density, HSD (30 m− 3) in triplicates. Fish were fed twice daily with CIFRI CAGEGROW® floating feed (crude protein-28%, crude fat-4%). Fish growth and feed efficiency was higher (P+, Cl− and K+) observed under crowding stress. Based on growth attributes and multiple biomarker responses, L. rohita @ 10 m− 3 found to be optimum density for inland open water cage culture.

The present study was conducted for 240 days to evaluate the effects of stocking density based on growth attributes, digestive enzymes, muscular composition, biochemical and physiological responses of Labeo rohita fingerlings in tropical inland open water cages. L. rohita (30.35 ± 1.08 g) were randomly distributed into three treatments, namely low stocking density, LSD (10 m−3), medium stocking density, MSD (20 m−3) and high stocking density, HSD (30 m−3) in triplicates. Fish were fed twice daily with CIFRI CAGEGROW® floating feed (crude protein-28%, crude fat-4%). Fish growth and feed efficiency were higher (p +, Cl− and K+) was observed under crowding stress. Based on growth attributes and multiple biomarker responses, L. rohita @ 10 m−3 was found to be the optimum density for inland open water cage culture.

Inhibins are members of the transforming growth factor beta (TGFβ) superfamily known to regulate ovarian functions through stimulation of the hypothalamo-pituitary-gonadal axis. In the present study, we aimed to design a species-specific inhibin-α chimeric peptide (ICP) and evaluate the effect of immunoneutralization using anti-ICP antisera to enhance the reproductive performance in female Clarias batrachus. Injection of anti-ICP antisera caused a significant increase in the number of oocytes at a medium dose (200 μl) in comparison to high dose (400 μl) and control (normal rabbit serum). Histological observations confirmed the dose-dependent advancement in oocyte maturation. Furthermore, anti-ICP antisera treated groups exhibited a significant increase in the serum concentrations of follicle stimulating hormone (FSH) and 17β-estradiol (E2) hormones. The anti-ICP antisera decreased the mRNA expression levels of inhibin-α while stimulated the transcript levels of inhibin-βA, FSHβ, CYP 19a1, 3β-HSD and StAR respectively in a dose-dependent manner. Collectively, these findings indicate that anti-ICP antibody macromolecules modulate the endogenous reproductive hormonal secretion and enhance oocyte quality and quantity in female C. batrachus. This is the first report wherein antibodies against inhibins were used to promote reproductive performances and investigate the underlying molecular mechanisms in fishes.

The present study was aimed to assess the effect of temperatures on egg incubation, growth, standard metabolic rate (SMR), and thermal tolerance of a near threatened Himalayan hill stream chocolate mahseer (Neolissochilus hexagonolepis). For the hatching study, eggs were incubated in four temperatures (17, 20, 23, and 26 °C). The total hatching and free-swimming larvae percentage were higher at 23 °C (p 0.05). Experiment I (for validation of the CTmax method) was carried out by incubating eggs at 17 °C and 23 °C. The CTmax was estimated in response to different warming rates (1-18°C h

This study aimed to investigate the effectiveness of five natural plant extract compounds Curcumin (CUR); Eugenol (EUG), Cinnamaldehyde (CIN), Stigmasterol (ST) and Morin (MOR), on two species of Saprolegnia; Saprolegnia parasitica and S. australis. Selective compounds were screened for the minimum inhibitory concentration, first for anti-oomycetes activity and then mycelium growth inhibition, spore germination inhibition and colonisation test. Nitric oxide production and myeloperoxidase activity of the compounds were tested in head kidney leukocytes of rainbow trout, Oncorhynchus mykiss to assess the immunostimulatory potential. Molecular docking of effective compounds was carried out with effector proteins of S. parasitica to investigate the target binding sites. Among all, CUR could completely inhibit zoospore production and significantly (p ≤ .05) inhibit hyphal growth at 16 mg l−1 against S. parasitica and S. australis. CIN at the concentration of 50 mg l−1 completely inhibited hyphal growth of both Saprolegnia spp., although the zoospore production of S. parasitica and S. australis was reduced at 25 mg l−1 and 10 mg l−1. In the case of EUG, significant inhibition of the hyphal growth and germination of S. parasitica zoospores was observed at 50 mg l−1. ST and MOR did not show antioomycetes activity. The molecular docking results were consistent with in vitro studies, possibly due to the binding with the vital proteins (Plasma membrane ATPase, V-type proton ATPase, TKL protein kinase, Host targeting protein 1) of S. parasitica and ultimately inhibiting their activity. CUR and CIN showed increased nitric oxide production at the highest concentration of 250 and 256 mg l−1 but the value was not significant (p ≤ .05) with control. CUR showed significantly higher peroxidase activity (p ≤ .05) at a concentration of 256 mg l−1 though values were significantly similar with concentration from 16 to 128 mg l−1. The nitric oxide and total peroxidase activity of rainbow trout leukocytes in the case of CIN showed a significant difference only at 250 mg l−1 against the control. The results conclude that CUR, CIN showed the better anti-Saprolegnia activity and could be used as phyto-additives in aquaculture. Among all, the inclusion of CUR as phyto-additives will provide additional immunostimulatory activity.

A 90 days trial was carried out to investigate the impact of stocking density on growth performances and the health status of Puntius sarana in inland open water cages (Salia Dam of Odisha, India). The fishes of mean body weight 32.04 ± 1.25 g were stocked @ three stocking densities (SD) i.e., 10 m−3 (SD10), 20 m−3 (SD20), and 30 m−3 (SD30) and fed with commercial feed of 28% protein and 4% fat. The growth, in terms of weight gain, specific growth rate, absolute growth rate, percentage survival, protein efficiency ratio, and feed conversion efficiency was significantly decreased (P

An 18-months field trial was performed to explore the effect of duration of stunting on growth, digestive enzymes and carcass quality in Chanos chanos. Milkfish fry (weight of 1.25 ± 0.03 g and length of 5.53 ± 0.03 cm) were stocked in earthen ponds of 0.02 ha, in triplicate, for different duration of stunting, viz., 4 months (Treatment-1; T4), 8 months (Treatment-2; T8) and 12 months (Treatment-3; T12) and a normal seed (Control; C) separately. In the stunting phase, fish were stocked at higher stocking density (0.2 million/ha) and fed de-oiled rice bran at sub-optimal level. Post-stunting or re-feeding phase commenced immediately after completion of respective stunting duration and fish were reared for the rest of the period to complete the total rearing period of 18 months. In post-stunting, fish stocking density was adjusted to (5000 pieces/ha) and fed at an optimum level (3%). At the end of stunting phase, the study found a significant reduction in growth, survival, digestive enzymes activity, except protease in the T4 group, and carcass nutrients composition of stunted fish. However, in the initial phase of post-stunting, T8 group exhibited an elevated specific growth rate (5.00 ± 0.092%/day), body weight gain (80.82 ± 1.28 g), amylase (0.585 ± 0.021 U/mg protein), protease (5.48 ± 0.13 U/mg protein), and lipase activity (7.92 ± 0.32 U/mg protein). All stunted fish groups displayed a compensatory growth response in post-stunting, but a complete growth compensation was observed in T8 group, which resulted in better feed conversion ratio (3.03 ± 0.04) feed efficiency ratio (0.33 ± 0.01), protein efficiency ratio (1.91 ± 0.03), survival (91.38 ± 0.07%) and digestive enzyme activities. Similarly, at the end of post-stunting, carcass analysis revealed a complete restoration of nutrients in stunted fish and significantly higher protein content in T8 group. Further, the study found lower meat and higher bone contents in normally reared fish than the post-stunted fish which revealed the carcass quality improvement in post-stunted fish thus indicates superiority of the stunting process over normal rearing. Overall, the study suggests that stunting of milkfish, for 8 months (T8), positively affects its growth, survival, digestive enzyme activities and carcass quality which in turn, shall help to overcome the contemporary challenges in milkfish culture.

Captive breeding programs for Neolissochilus hexagonolepis are essential for population restoration. To develop an efficacious method for enhancing N. hexagonolepis spawning in captivity, there was examination of: (1) different types of spawning substrate and (2) area of spawning in the substrate. The study was conducted to describe spawning behavior of males and females. There was a choice of three substrates in which to spawn: gravel, small cobble, and coarse sand. There was preferential choosing of gravel followed by cobble with there being no use of sand for spawning. Behavior of N. hexagonolepis included preparation of a spawning pit by females, a behavior that has not been previously ascertained for cyprinids. Males expressed courting behaviors, including chasing, nudging, and quivering. Courting males expressed aggressive behaviors towards other males. Results from the present study are the first on the volitional spawning of N. hexagonolepis in captivity using spawning substrate. It was further revealed that using a gravel substrate tray would also be a feasible approach for egg production. Mean total eggs per female and mean fertilized eggs collected were less when there was siphoning used for egg collections in the preference study. Hence, stripping was implemented to increase the egg collection when spawning behaviors were observed. Total eggs collected were 40,540 with 3685 eggs per female, 90.3% fertilization rate, 82.8% hatching rate, and 97.4% free-swimming larvae survival rate. The implications of this study could be beneficial for enhancing the natural population through environmental management and developing a viable egg production technique in captivity.

This study investigated the effect of dietary supplemented synthetic, and shrimp shell meal (SSM) derived natural astaxanthin combination on growth, digestive and metabolic enzyme activities, antioxidative status, physio-metabolic responses, and skin colouration of high valued discus (Symphysodon aequifasciatus) advanced juveniles reared in captive condition. Four isonitrogenous (50 % crude protein), isolipidic (9% ether extract), and isocaloric (around 400 kcal digestible energy/100 g) experimental diets viz. Control (only synthetic astaxanthin, without SSM), T1 (15 % SSM + synthetic astaxanthin), T2 (20 % SSM + synthetic astaxanthin), T3 (25 % SSM + synthetic astaxanthin) were prepared and fed to satiation level twice daily for 90 days. Results indicated significantly (P

The false clown fish, Amphiprion ocellaris is a promising candidate species in the global marine aquarium trade. The lack of sustainable hatchery production and the over-exploitation from the wild cause severe threats to their natural population. Environmental factors influence the survival and existence of aquatic animals, and the temperature is one of the most crucial factors determining survival, especially during the early embryonic developmental stages. The present study evaluated the effect of temperature on embryonic development by exposing the fertilized eggs to varying temperature (26 °C, 27 °C, 28 °C, 29 °C, and 30 °C). Temperature significantly (P

Diel cyclic hypoxia occurs with varying frequency and duration in freshwater habitats, yet little is known about its effects on reproduction of freshwater fishes. The present study shows that long-term exposure of goldfish (Carassius auratus) to cyclic hypoxia (0.8 ± 0.2 mg/l dissolved oxygen) for 9 h or more, per day, altered plasma lipid and sex steroid profiles, which in turn directly or indirectly suppressed ovarian growth and viable spermatozoa production. Hypoxia decreased total cholesterol and high density lipoprotein (HDL p

Impact of osmoregulation on plasma sex steroid levels and gonadal histo-architecture was monitored to elucidate the effects of deviation from habitat salinity on gonadal recrudescence in an active reproductive season of an euryhaline fish Etroplus suratensis (pearlspot). Fish were maintained in three different salinities of 0 ppt Fresh Water (FW), 15 ppt Brackish Water (BW) and 30 ppt Sea Water (SW) for a period of 60 days. Plasma osmolality values were found to be significantly highest in SW-acclimated fish accompanied by highest levels of plasma K⁺ and Cl¯ ions. The progress of gonadal recrudescence was higher in BW followed by FW and SW as evident from the cellular features of gonads and increased level of plasma sex steroids, such as, in case of female and 11-keto Testosterone and Testosterone in case of males. Plasma cortisol levels were comparatively higher in fish of both sexes in SW group. Significantly high levels of cortisol in SW suggest its role in hypo-osmoregulation and associated stress. This study clearly reveals that salinity changes during the active reproductive phase can suppress the steroid-mediated gonad recrudescence maximally under hypo-osmoregulation in an euryhaline fish.

Three hydroponic media crushed stones (T1), river stones (T2), and floating raft (T3) were compared in an aquaponic system with common carp (Cyprinus carpio) and mint (Mentha arvensis). Fish effluents were used as plant nutrients while plants filtered water by stripping off the nutrients before returning to the fish tank. Fish growth, plant growth, and water quality parameters were used to evaluate the suitability of three different media. Growth performance of common carp and mint followed the relationship of crushed stones > floating raft > river stones with significant difference observed among all treatments. Total ammonia nitrogen (TAN) removal varied significantly among different treatments. The maximum TAN removal was observed in T1 (77.13%) followed by T3 (69.65%), and the minimum removal was observed in T2 (48.82%). Nitrate removal varied significantly among different treatments. The highest removal was observed in T1 (82.95%) followed by T3 (68.04%) and T2 (59.51%). Removal of phosphate was significantly lower in T2 (50.12%) when compared to T1 (67.85%) and T3 (70.71%). Biofilter performance (g m−3 day−1) of T2 (4.80) was significantly lower compared to T1 (7.13) and T3 (7.37). Crushed stone and floating raft were significantly efficient when compared to river stone medium in terms of nutrient removal and water quality maintenance for the fish culture. Considering all growth parameters, crushed stone media proved to be better when compared to other two media. Thus, medium selection could be a considerable factor when designing an aquaponic system.

An experiment of 36 days duration was conducted to study growth performance of goldfish Carassius auratus and basil Ocimum basilicum reared in a media bed aquaponic system. Goldfish fry (3.32 ± 0.45 g and 4.20 ± 0.39 cm) were stocked in rectangular 75 l capacity (water volume of 50 l) plastic tanks at three different stocking densities viz., 500 m-3 (T1), 600 m-3 (T2) and 700 m-3 (T3), respectively and basil plants were planted at a density of 20 m-2, i.e., 10 plants 0.44 m-2 in the rectangular plastic tanks filled with crushed stone media. The goldfish fry were fed with artificial feed (33% protein) at 5% of body weight in equal proportions, two times a day. Control (C) group was set with only basil plants. Growth parameters of goldfish such as length gain (%), weight gain (%) and specific growth rate (% d-1) were significantly higher in T3 (p

In this study, we investigated the effect of dietary Bacillus circulans PB7 (BCPB7) and fructoligosaccharide (FOS), used singly or in combination for evaluation of growth, immune and physiological status of Labeo rohita (rohu) juveniles reared under low pH and normal pH for 60 days. Experimental fishes were distributed in two sets such as one set continuously exposed to low pH (5.5) and other reared under normal pH (7.0), and fed with four iso-nitrogenous diets viz. basal (control), Bacillus circulans PB7 (BCPB7, 106 cfug−1), 1% fructooligosaccharide (FOS) and their combination. The effect of such pre, pro and synbiotics dietary treatments on growth performance (weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio), immune response (hematological indices, serum biochemistry, lysozyme, NBT activity), antioxidative status in the form of antioxidant enzyme (catalase, superoxide dismutase, glutathione-S-transferase), acetylcholine esterase (AChE), Na+ K+ ATPase and stress bio-markers (cortisol, glucose and HSP-70) were examined. The group treated with low pH and fed with control diet (without supplementation) was found to be inhibited (p

Carotenoprotein, a complex of carotenoids and protein, extracted from shrimp shell waste can be an effective source of carotenoid as well as antioxidant in fish diets. In the present study, the nutritional potential of carotenoprotein extracted from shell wastes of Parapeneopsis stylifera on growth, physiometabolic changes and coloration in high-value ornamental fish, oscar (Astronotus ocellatus) was assessed in a 120 days feeding trial. Four iso‑nitrogenous (30–31% CP) and isolipidic (11.34–11.55% CL) diets were formulated with graded levels of carotenoprotein inclusion like 0%, 5%, 10% and 15% and designated as Control, T1, T2 and T3 respectively. At the end of the feeding trial, growth indices such as final body weight, weight gain, and specific growth rate indicated that fish fed with 10 and 15% levels of carotenoprotein incorporated diet showed higher growth compared to control and T1. Oxidative stress enzymes like SOD and Catalase were lower in 15% and 10% carotenoprotein incorporated diets respectively in both gills and liver. Stress indicators like serum glucose and cortisol activity were found to be higher in control than in diets with 10% (T2) as well as 15% (T3), suggesting the stress-reducing ability of the carotenoprotein in fish feed. Relatively higher respiratory burst activity in fishes of T3 group indicated higher immunity status of the fish. Quantitative colour values in terms of redness, chroma in the fin region as well as carotenoid content in scale, skin and muscle of fish were higher in T2 (10% carotenoprotein incorporated diet) as compared to T3 (15% carotenoprotein incorporated diet). Overall, this study clearly showed that dietary incorporation of as little as 10% carotenoprotein is advisable to ornamental fish farmers for enhanced growth, colouration, as well as antioxidant activity in this popular high value ornamental fish for maximizing their profit.

Temperature can influence sex differentiation in gonochoristic fish with a genetic sex-determination system (GSD). The precise effect of high temperature on sex remains unknown in a eurythermal carp (Cyprinus carpio). The present study aimed to identify the critical thermosensitive period and the effect of temperature on sex differentiation in common carp, C. carpio. Our results demonstrated the lower and upper limits of the lethal maximum temperature (LTmax) of C. carpio juveniles (42 dph) were 37.2 and 39.7 °C, respectively in the present study condition. The confidence limit of the median lethal time (LT50) of the juveniles was 38.87 °C. To determine the thermosensitivity of sex differentiation, the larvae were exposed to a high temperature (36 °C) for 7-day durations, starting from hatching until 69 dph. The period of critical thermosensitivity for sex differentiation towards the male phenotype was 7 to 13 dph. The sex proportions and thermosensitivity of sex differentiation illustrated high inter-familial variability of sex ratio skewed towards male phenotype ranged from 69 to 100% in the 10 full-sib families exposed to 36 °C. Exposure of juveniles to the high temperatures (34 °C and 36 °C) significantly altered the sex ratios and produced 63 to 82 % male phenotype even during the transition of sex differentiation. This study demonstrates that sex differentiation in common carp is seriously influenced by the environmental process. Also, it explores a temperature-induced method of skewing sex ratio towards the male phenotype irrespective of morphological gonad differentiation in common carp.

A 60-day feeding trial was performed to test the nutritional value and utilization possibility of palm kernel meal (PKM) as a feed ingredient for juvenile Labeo rohita. Five iso-nitrogenous diets were prepared with various inclusions of PKM which replaced sunflower oil cake and de-oiled rice bran namely, control (without PKM), T1 (50 g/kg PKM), T2 (100 g/kg PKM), T3 (150 g/kg PKM) and T4 (200 g/kg PKM). The experiment was conducted in 350 L fibre reinforced plastic tanks in triplicate and each tank stocked with twenty-five juvenile rohu (7.2 ± 0.01 g) were fed twice daily at 5% of body weight with the experimental diet. The growth performance values showed a higher overall linear trend in T2 and it is significantly different from control as well as T1 groups. Final results showed highest average body weight, specific growth rate, protein efficiency ratio, and apparent net protein utilization in a dose-dependent manner (p < 0.05). Significantly higher amylase, protease, and lipase activities were recorded in T2 treatment (p = 0.003, p = 0.001 and p = 0.002, respectively). Additionally, dietary PKM significantly lowered the aspartate amino transferase, alkaline amino transferase and alkaline phosphatase enzyme activities in a dose-dependent manner (p < 0.05). Significantly higher lactate dehydrogenase, malate dehydrogenase, superoxide dismutase and catalase activities in the liver tissues were recorded in T4 (p = 0.004, p = 0.01 and p = 0.02 and p = 0.001, respectively). Based on the polynomial regression analysis, the PKM inclusion at 26.17–100.11 g/kg can be effectively used in the diet of juvenile L. rohita as a non-conventional growth-promoting feed ingredient without any harmful effects on its growth performance and physiological activities.

The golden mahseer (Tor putitora) is an important and high valued sport and food fish of national and international importance. Therefore for promotion of golden mahseer, proper mineral supplementation in early developmental stages is very important. The present study evaluated the effects of dietary zinc on growth, survivaland physiological response of Tor putitora fry. One thousand eight hundred fry (avg.wt 54.35±3.09 mg) were randomly distributed into 6 treatment groups with triplicates each. Six iso-nitrogenous (40±0.02% to 41.44±0.01% crude protein) semi-purified diets were prepared with graded levels of dietary zinc. Zinc sulphate was added as the dietary zinc source to the basal diet. The results indicated that specific growth rate (SGR) was of value 2.52 ±0.23 gm of T. putitora fry which increased with dietary zinc levels up to a concentration of 40 mg Zn Kg-1 in diet. The zinc dependent metabolic enzymes and antioxidant enzymes was also observed to be highest in groups supplemented with 40 mg zinc/kg feed. The overall results of the present study suggest the efficacy of dietary zinc on growth, survival and physiological response of golden mahseer fry in order to garner the possibility of establishing the species to commercial aquaculture.

Aquaponics is the combined culture of fish and plants in recirculating aquaculture systems, considered to be an innovative, eco-friendly and sustainable technology. The present study on bio-integration of Common carp and Mint in aquaponic system was aimed at determining the optimum hydraulic loading rate (HLR) for the aquaponic system. Three treatments having different HLRs viz., T1 (3 m day−1), T2 (6 m day−1) and T3 (12 m day−1) were compared and their effect on fish growth, survival, mint growth, yield and various water quality parameters were observed to find the most efficient HLR for Common carp and Mint in aquaponic system. Different HLRs showed significant effect on fish growth in terms of length and weight gain, survival, specific growth rate (SGR). Higher growth rate was observed in treatment T2 (6 m day−1) as compared to other treatments and control having different HLRs. Mint growth rate at the end of both the harvests showed significant variation and got affected by different HLRs with better results obtained in treatment T2 (6 m day−1). Overall water quality parameters, nutrient removal and biofilter performance were better at HLR 6 m day−1 i.e., treatment T2. Hence, HLR of 6 m day−1 can be recommended for culturing Common carp and Mint in aquaponic system.

An experiment was conducted to compare the efficiency of biofilm production in natural and artificial substrates and to study their effect on water quality and growth of Etroplus suratensis. Four different substrates were used for biofilm formation: paddy straw (T1), sugarcane bagasse (T2), polyvinylchloride (PVC) pipe (T3) and plastic sheet (T4). The experiment was carried out in mud-bottomed fibre-reinforced plastic tanks (300 L) in triplicates. About 3000 cm2 surface area (600 g) of each substrate was suspended in water supplemented with fertilizers. Only cow dung and urea were applied in control tanks. The tanks were stocked with 25 fishes with average weight of 9.1 ± 0.22 g. The overall mean value of heterotrophic bacteria in substrate was found higher in straw followed by bagasse, plastic and PVC. The dominant genera of bacteria in the substrate were Bacillus, Pseudomonas and Micrococcus in that order of preponderance. The mean phytoplankton and zooplankton density on the substrates were higher in bagasse followed by straw, plastic and PVC. The biofilm developed on the substrate significantly reduced the ammonia nitrogen and nitrite-nitrogen content of water. The growth of fishes was significantly (P