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The global ornamental fish trade is expanding in response to increased demand for indigenous fish on the global market, while exogenous carotenoids can improve colouration. The 60‐day trial investigated the effect of carotenoid supplementation, via Artemia, on colouration, growth and immunophysiology of Badis badis (dwarf chameleon fish). Carotenoid was enriched at 40 ppm (T1), 80 ppm (T2) and 120 ppm (T3) and compared with controls, C1 (unenriched) and C2 (oil‐enriched). Fish larvae (average weight 0.12 g) were fed enriched–unenriched Artemia in triplicates (5 × 3) in aquarium tanks (15 L). C1 and T2 had better skin colour (lightness and whiteness) in the posterolateral and caudal fins respectively. The value of redness (a*) in the anterolateral region was higher in T2 and T3 (p < 0.05). The anterolateral red index was higher (p < 0.05) in T2 and T3, whereas in the posterolateral and caudal fins, T1 and T2 were higher (p < 0.05). Compared to C1 and C2, the hue angle in carotenoid groups was found to be low (p < 0.05). No significant change in the growth performance was noticed (p > 0.05). Immune scores such as lysozyme and alkaline protease were highest in T3 (p < 0.05), whereas protease activity was highest in T2 (80 ppm). Stress biomarkers, viz., superoxide dismutase, catalase and malondialdehyde were low in groups fed enriched Artemia (p < 0.05). The integrated biomarker response means and star plot area were lower in the enriched groups (T1–T3), while T2 was the lowest. Overall findings reveal that dietary carotenoid improves the colouration and immune status, but fail to promote growth. Furthermore, 80 ppm enrichment dose improves the overall performance. The findings can help fish keepers improve fish colour and health status through carotenoid supplementation. [ABSTRACT FROM AUTHOR]

The objective of this study was to reveal the growth, colouration and gonado-physiological changes due to the exogenous aromatase inhibitor (AIs) in an ornamental fish. 17α-methyltestosterone (MT) and letrozole (LET) were used as potential AIs. The AI were supplemented with a gel-based feed (LET: 50, 100, 150 and MT: 12.5, 25, 37.5 mg/kg feed) in Rosy barb, Pethia conchonius fry. The fishes were reared in a 45-L glass tank using AI treated gel-based feed for 3 months. Growth in AI-based diets was reduced but the reduction was minimal compared to the control. At 25 mg/kg feed of 17 MT, the highest male proportion (84.72% 6.05%) was recorded, which was significantly higher (P≤0.05) than other groups. L*, a*, and b* values showed that 17α-MT-fed groups had brighter coloration (P≤0.05). Histological sections showed that LET-17α-MT suppressed ovarian development, causing atretic oocytes. Testicular development was unaffected. 25 mg/kg-treated feed increased SOD, CAT, GST, and GPX. The AI (MT) at 25 mg/kg gel-based feed could therefore be utilised for musculinization without impacting growth, colour, and antioxidant activity of rosy barb, which serves the entire male population in the ornamental fish sector. [ABSTRACT FROM AUTHOR]

To resurrect and establish a low-impact aquaculture practice, gel-based feed applications hold promise. Gel feed is viscoelastic, nutrient-dense, hard, flexible, and appealing, and can be moulded into appealing shapes to ensure rapid acceptance by fish. The purpose of this research is to create a suitable gel feed using various gelling agents and to evaluate its properties and acceptance by a model fish, Pethia conchonius (rosy barb). Three gelling agents, viz. starch, calcium lactate and pectin, were included at 2%, 5%, and 8% in a fish-muscle-based diet. The physical properties of gel feed were standardized using texture profile analysis, sinking velocity, water and gel stability, water holding capacity, proximate composition, and colour. The lowest levels of nutrient leaching protein (0.57 ± 0.15%) and lipid (14.3 ± 14.30%) were observed up to 24 h in the underwater column. The highest score for overall physical and acceptance characteristics was noted for the 5% calcium lactate-based gel feed. Furthermore, a 20-day acceptance feeding experiment was conducted using 5% calcium lactate to examine its suitability as fish feed. The results indicate a better acceptability (3.55 ± 0.19%) and water stability (−2.5 ± 2.5%) of the gel feed compared to the control, with an improvement in nutrient losses. Overall, the study provides an insight into the application of gel-based diets for ornamental fish rearing, besides ensuring an efficient nutrient uptake and minimal leaching to establish a clean aquatic environment. [ABSTRACT FROM AUTHOR]

Biofloc technology is a modern-day high-density fish culture system employing heterotrophic conversion of nitrogenous waste into useful flocs for water quality control and improved welfare. However, optimization of the stocking density for the target species during seed rearing is the key to a successful farming operation. The study evaluated the effect of different stocking density on the growth, feed utilization, digestive physiology and economics in a biofloc-based seed rearing of butter catfish, O. bimaculatus. Advanced fry (1.21 ± 0.08 g) was reared in a zero-water exchange biofloc system for 90 days at stocking densities of 0.5 g/L(T1), 1.0 g/L(T2), 1.5 g/L(T3) and 2.0 g/L(T4). The observed water quality indicates a reduction in DO and pH in T4, while the total ammonia nitrogen and nitrite levels remained low in T1. Among the groups, highest weight gain was noticed in the lowest stocking density (0.5 g/L) (p < 0.05), which coincides with a better feed conversion ratio. Similarly, the digestive enzyme (protease, amylase, and lipase) secretion was higher in T1. Profitability assessment describes the possibility of low profit in T4, in the case where the fish's sale price is based on harvested size. T1 showed higher individual growth and higher profit. Overall, a low stocking density of 0.5 g/Lis optimum for augmenting growth, feed utilization, physiological function and economic performance of O. bimaculatus. The study provides direction for a low-stocking oriented ecological and economically sustainable method of seed production of butter catfish in a biofloc system. [ABSTRACT FROM AUTHOR]

The experiment was carried out in eighteen outdoor cemented tanks (5m × 4m × 1m) for a period of 100 days at College of Fisheries, Lembucherra to evaluate the length-weight relationship and condition factor of Labeo catla, Labeo rohita and Labeo gonius were worked out under different treatment. Tanks were initially dried, cleaned and treated with quick lime (CaO) at the rate of 200 g/tank and then filled with ground water. After a week of liming all the tanks were fertilized with cow dung at a basal dose of 2 kg/tank. Fertilization dose were the same for all the treatments. The tanks were provided with a soil base of 6-8 cm. The fingerlings of Labeo catla (Hamilton, 1822) were obtained from local farmers, Labeo rohita (Hamilton, 1822) and Labeo gonius (Hamilton, 1822) were collected from the rearing ponds and were stocked in 18 experimental tanks at three different stocking densities, viz. 1 no.m-2, 2 nos.m-2 and 3 nos m-2 at a stocking ratio of 1:1:1 in uniform size with and without feeding treatment having 3 replicates. Physico-chemical parameters of the experimental tank were taken 20 days interval and were within the normal ranges for fish culture. Length –weight relationship for T2 treatment were shows higher value than other treatment 0.558 L2.796 for catla, 0.844 L 2.663 for rohu and in case of gonis 0.713 L1.853. Feeding treatment shows higher b values (2.796 for catla and 2.663 for rohu at T2 treatment and 1.853 for gonius at T4 Treament) than without feeding treatments even though all the treatment were treatment negatively alometric value. The ‘b’ value of different treatment were lower than critical isometric value i.e. 3.0 indicating negative allometric growth pattern in all species under different. [ABSTRACT FROM AUTHOR]

A major challenge in Clariid catfish seed production is our inability to induce voluntary captive spawning of the brooders. Since voluntary captive spawning had been previously elicited in a Clarias species by simulating natural breeding environment, we speculated that the major obstacle in voluntary spawning might be the absence of an inducing agent that triggers mating response in the brooders. To address the issue, oxytocin was injected to the brooders along with Ovatide (a commercial inducing agent comprising salmon gonadotropin‐releasing hormone analogue and domperidone). Administration of 40 mIU/kg body weight of oxytocin after 12 hr of Ovatide injection resulted in voluntary spawning of the fish (81.5%, i.e. 31 out of 38 trials), with more than 70% hatching rate in simple and low‐cost spawning facilities. Histology of male gonads indicated sustained gamete maturation and the gonads were observed to be visibly turgid in the fish that received both the hormones. In contrast, gamete maturation slackened after 10 hr in the control fish, injected with Ovatide only. Administration of oxytocin along with Ovatide was also observed to induce aggressive sexual behaviour among the males. Neither of the hormones, acting alone, could induce voluntary spawning in the fish or influence sexual behaviour. Our results clearly show that oxytocin plays a significant role in sustaining the male gamete maturation induced by Ovatide and trigger the behavioural mating response, leading to voluntary spawning in C. magur. The results hold potential to make a paradigm shift in the commercial catfish seed production technology. [ABSTRACT FROM AUTHOR]

Larval growth and survival of catfishes are largely influenced by the various biotic and abiotic factors. The present study investigated the effect of different light intensities and photoperiods on growth and survival of Ompok bimaculatus larvae. Three separate trials of 21 days each were carried out in an aquarium tank. The first trial investigated the embryonic changes (based on hatching rate and time) upon exposure to varied light intensity (0, 300, 500, 900 and 1200 lx) and photoperiodic regime (24l:0d, 16l:8d, 12l:12d, 8l:16d and 0l:24d). Subsequently, hatched‐out larvae were subjected to the aforementioned intensities (Trial II) and photoperiod (Trial III, intensity of 300 lx) for growth and survival attributes. Eight hundred healthy larvae (average body weight = 0.003 g) were randomly distributed into five treatment groups for the last two trials. Results suggest a higher embryo hatching rate and larval survival at 0 and 300 lx, whereas the largest larval growth was observed at 900 lx. In Trial III, survival was highest in 0l:24d and growth in 24l:0d and 16l:8d was higher (P < 0.05). Performance index was higher (P < 0.05) in both 0 and 300 lx light and decreased at higher intensities. The overall interpretation from the present study concludes that a completely dark rearing environment is recommended for better survival of O. bimaculatus although growth was compromised. [ABSTRACT FROM AUTHOR]

A 60-d feeding trial was conducted to assess the dietary protein requirement of Indian Butter catfish, Ompok bimaculatus fingerlings. Five iso-energetic semi-purified diets were formulated with varying levels of crude protein (25–45%) and fed to the experimental fish (3.29 ± 0.01 g) twice daily at satiation level in triplicate groups. Fishes were reared in indoor tanks with a stocking density of 11 fingerlings per tank. The results showed that the growth of the fish increased significantly (P <.05) with increasing protein levels upto 35% and decreased thereafter. Highest (P <.05) weight gain (247.25 ± 5.76%), carcass protein content (16.78 ± 0.04%) and protease activity (0.46 ± 0.02) coupled with lowest FCR (1.62 ± 0.04) were observed in the fish fed with 35% protein. PER and ANPR were found to decrease with increasing dietary protein levels (P <.05). Based on the second-order polynomial regression analysis of WG, it may be concluded that the dietary protein requirement of O. bimaculatus is 36.11% with a P/E ratio of 23.11 g protein MJ−1 as indicated by the maximum growth. [ABSTRACT FROM AUTHOR]

An experiment was designed to evaluate the requirement of dietary protein for Reba carp, Cirrhinus reba fingerlings using semi‐purified diet. Five isocaloric diets were prepared containing 20%, 25%, 30%, 35% and 40% level of protein using casein, gelatin as a major protein source. The experiment was conducted for 105 days in triplicates to evaluate the growth, survival, feed utilization, carcass composition of C. reba. Mean weight gain was highest (p < .05) in T3. Specific growth rate was highest in T3 and lowest in T1. Similarly, significantly (p < .05) highest net fish yield were recorded in T3. No significant difference was recorded in survivability. Feed conversion ratio, protein efficiency ratio, feed conversion efficiency and protein conversion efficiency were significantly (p < .05) higher for T3 compared with other treatments. Highest carcass protein and lipid values were recorded in T3. So, conclusion can be drawn that 30% crude protein is optimum for overall performance. Furthermore, broken‐line analysis for specific growth rate, final biomass and net fish yield indicated that dietary protein level of 28.148 to 28.253% is optimum for the best growth performance of fingerling C. reba. [ABSTRACT FROM AUTHOR]

A 30-day experiment was conducted to assess the effect of tryptophan-supplemented diets on growth and survival of Pabda, Ompok bimaculatus fry. Fifty pabda fry (0.114 ± 0.02 g; 2.45 ± 0.13 cm) were stocked into each aerated aquarium following a completely randomized design consisting of four treatments with triplicate each. Four iso-proteinious purified diets were prepared with different levels of tryptophan—0%, 1%, 2%, and 3%—of the dry diet and were designated as Control, TRP1, TRP2, and TRP3 respectively. Fishes were fed with the experimental diet ad libitum four times a day. The results showed that fish fed with tryptophan-supplemented diets exhibited significantly (P < 0.05) lower cannibalism and higher survival than the control diet. Further, the tryptophan-supplemented groups showed a significantly lower coefficient of variation (%) and size heterogeneity (P < 0.05). However, the growth as measured by body weight gain, length increment, and specific growth rate of fry in tryptophan-supplemented groups was significantly lower than the control group (P < 0.05). Moreover, maximum survival (52.67 ± 1.76%) and minimum cannibalism (21.33 ± 5.70%) coupled with higher growth and performance index (0.38 ± 0.01) were recorded in the 2% tryptophan-supplemented group compared to other tryptophan-fed groups. Overall interpretation from the present study concludes that the dietary supplementation of 2% tryptophan is recommended for better survival of pabda fish, although growth was compromised. [ABSTRACT FROM AUTHOR]

A 40 days feeding trial with Labeo rohita (rohu) fry was conducted in six outdoor cemented tanks (5m × 4m × 1 m; 6–8 cm soil base) to establish the relative impact of on‐farm grown live Wolffia globosa (a duckweed with crude protein of 28.57%) and a formulated iso‐nitrogenous feed (crude protein 28.37%) on growth performance, survival, health and overall quality of fingerlings. The experimental tanks were dried, limed at 250 kg/ha, filled with ground water and subsequently applied with cow dung (soaked overnight) and mustard oil cake at 1,000 kg/ha and 50 kg/ha respectively. The fry were stocked at 0.3 millions/ha in six prepared tanks, and fed live Wolffia (T1) and formulated feed (T2). Results of the study indicate better performance (p < 0.05) of fry in terms of final mean weight (7.83 g), length (8.82 cm), daily growth index (6.51 g %/day) and survival (89.5%) than those fed on formulated feed. Furthermore, significantly improved (p < 0.05) feed utilization parameters viz. apparent feed conversion ratio (AFCR), apparent protein conversion efficiency (APCE), apparent protein efficiency ratio (APER); haematological parameters viz. total erythrocyte count (TEC), total leucocyte count (TLC), packed cell volume (PCV), plasma glucose and protein of fry were also observed in T1 (live Wolffia). Overall findings from this study hints towards the possible utilization of on‐farm grown live Wolffia as a suitable nutrient source for fry rearing of L. rohita. [ABSTRACT FROM AUTHOR]

The present study describes a simple, portable, and inexpensive in-pond hatchery model assembled from locally available materials for seed production of small and medium-sized carp at high efficiency. This light-weight hatchery requires minimal engineering skills for assembly and operation. Further, the hatchery water supply mechanism has built-in components to filter out sediments and zooplankton from the pond water besides maintaining the water temperature 5°C–7°C lower than the pond surface water by drawing water from a metalimnion layer without additional energy requirements. Spontaneous spawning, automatic transfer of eggs to the incubation tank, and 80% hatching rates at an egg-holding capacity of 2,000 eggs/L was recorded forBarbonymus gonionotus, Labeo bata, andLabeo rohitawith minimal human intervention. The production capacity of 0.06 million fry per cycle and estimated benefit-cost ratio of 2.48 demonstrated the high efficiency and economic feasibility of this portable hatchery. [ABSTRACT FROM PUBLISHER]

This study aimed to evaluate the effect of vitamin E on the reproductive responses and the expression of reproductive genes in butter catfish (Ompok bimaculatus). Diets with different levels of vitamin E supplementation (0, 100, and 150 mg/kg) were provided to groups of fish for 60 days. After rearing for 60 days fish were induced with synthetic hormone, that is, Ovatide to study the breeding performance. Ovatide was administrated intramuscularly at the rate of 0.5 and 0.25 mL/kg of body weight for females and males, respectively, in all the treatments. Breeding performance result shows that supplements of vitamin E positively influenced the GSI%, fertilization rate, fecundity, and hatching rate. To understand the relationship between vitamin E and the breeding performance of the fish at the molecular level, a gene expression study was conducted. This study employed real‐time PCR for the selected genes critical for reproductive function. In the brain, testis, and ovary dietary vitamin E supplementation of 100 mg/kg significantly enhanced the mRNA transcription of FSHR, Brdt, ESR1, 17beta2, and LHR. Hence, it can be said that 100 mg/kg of vitamin E supplementation in the diet during the reproductive period of O. bimaculatus could improve breeding performance and the mRNA expression of reproductive hormone receptor genes in both males and females of O. bimaculatus. [ABSTRACT FROM AUTHOR]