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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]

Purpose: The influence of two key factors, host length and infection site, on the host-parasite interaction in Ompok bimaculatus (Butter catfish) from Mukutmanipur Dam Lake, were investigated. Methods: Present study involved 192 specimens of Ompok bimaculatus with varying body lengths, subjected to diverse statistical analyses. One-way analysis of variance (ANOVA) was performed for the parasite numbers for three groups (cestode, nematode and trematode). Subsequently, we conducted one-way permutational multivariate analysis of variance (PERMANOVA) followed by pairwise test to assess parasite numbers across three body sites (intestine, mesentery, and bodycavity), employing the Bray-Curtis index. Additionally, Principal Coordinate Analysis (PCoA) for the same dataset was performed using the same index. Linear regression analysis was performed for the fish length-cestode number, fish length-nematode number, fish length-trematode number and fish length-total parasite number. Results: One-way ANOVA revealed no significant differences in parasite numbers among the three endo-helminth groups (cestode, nematode, and trematode). The results of PERMANOVA revealed significant differences in parasite numbers across the three body sites of the host fishes (groups) (F = 9.41, p = 0.0001). Pairwise tests further demonstrated significant differences between the intestine-mesentery, intestine-body-cavity, and mesentery-body-cavity. Additionally, Principal Coordinate Analysis (PCoA) unveiled a significant relationship between infection site and parasite number. However, linear regression analysis examining the relationship between fish length and parasite abundance indicated no significant associations. Conclusions: Through a detailed exploration of the statistical analyses, we provide insights into the host-parasite interaction, elucidating both established knowledge and novel findings in fish parasitology. [ABSTRACT FROM AUTHOR]

In vertebrates, insulin-like growth like factors (IGFs) play an important role in growth and other physiological processes. The GH-IGF axis is considered a valuable tool to monitor fish growth performance. Herein, we report the molecular characterization of igf-1, igf-2, and β-actin transcripts and relative expression of igf-1 and igf-2 in the liver and muscle tissue of cage-reared butter catfish, Ompok bimaculatus, in response to different stocking densities (T1, 15 fingerlings m−3; T2, 25 fingerlings m−3; and T3, 35 fingerlings m−3) over 180 days of culture duration. The length of the partial amplified transcript sequence of Obigf-1, Obigf-2, and Obβ-actin was 325, 438, and 924 bp, respectively. Phylogenetically, Obigf-1 and Obigf-2 were closely clustered with catfishes, viz., Clarias magur, Bagarius yarrelli, and Silurus asotus. The expression of igf-1 was significantly downregulated in the liver at higher densities after 120 days as biomass in the cages increased, while igf-2 expression did not change with the stocking densities over the culture period. Cortisol concentration was significantly elevated in T3 groups post 150 days of the culture period and correlated negatively with the expression of igf-1 (p < 0.05) and igf-2 (p > 0.05). Environmental parameters, pH, TDS, hardness, conductivity, and alkalinity showed a significant positive correlation with hepatic IGF expression. Our study indicates that the liver-derived igf-1 plays a more important role in the regulation of growth in response to culture density in the species studied, and thus, igf-1 can be used effectively as a biomarker for growth. Furthermore, this study will help in planning a proper harvest schedule and optimize the culture practices of O. bimaculatus in an open water cage system. [ABSTRACT FROM AUTHOR]

A completely randomized 3 × 3 factorial feeding trial was conducted to evaluate the effects of dietary protein and lipid levels on growth, feed utilization, body composition, and digestive as well as metabolic enzymes of the butter catfish (Ompok bimaculatus) fingerlings. Fish (average weight 0.66 ± 0.12 g; 30 d) were fed nine experimental diets containing three protein levels (35%, 40%, 45%) and three lipid levels (5%, 10%, 15%) in triplicate groups for a period of 90 days. The formulated diets were named P35L05, P35L10, P35L15, P40L05, P40L10, P40L15, P45L05, P45L10, and P45L15 (P = Protein; L = Lipid) respectively. The results indicated no protein-sparing effect of lipid in O. bimaculatus fingerlings beyond 35% dietary protein. Overall, diets P40L5 and P35L10 had significantly (P < 0.05) higher SGR (% day−1) and lower FCR than other experimental groups. The highest weight gain (10.89 ± 0.07 g) and carcass protein (16.71 ± 0.2%) were recorded in fish fed diet P40L05. Increasing dietary lipid levels brought about an increase in carcass lipid in fish. Activities of α-amylase and acid-protease were decreased (except at 5% lipid), whereas alkaline-protease was increased with increasing dietary protein. An increase in pyruvate kinase (PK, glycolytic enzyme) activity and decrease in glucose-6-phosphate dehydrogenase (G6PD, lipogenic enzyme) activity were noticed with increasing dietary lipid content. A decrease in PK and increase in G6PD activities were observed with increasing dietary protein levels. Activities of the gluconeogenic enzymes (glucose-6-phosphatase, fructose-1,6-phosphatase) increased significantly (P < 0.05) with increasing dietary protein and lipid levels. Amino acid catabolizing enzymes, alanine transaminase and aspartate transaminase, were slightly increased with increasing dietary protein levels. Considering growth, body composition, metabolic function, and survivability (>95%), the diet containing 40% crude protein with 5% lipid might be suggested as optimum for O. bimaculatus fingerlings under the tested conditions. [ABSTRACT FROM AUTHOR]

Scientific research into fish wellness is critical, and the concerns about crowding-related stress due to increased stocking density are inevitable. Taking this into consideration, the study defines the physiological signature of Ompok bimaculatus (Butter catfish) in a biofloc system when subjected to varying levels of stocking density. Fish (mean weight = 1.21 g ± 0.08, n = 600) were randomly stocked in 40-L glass aquaria at stocking densities of 0.5 g/L (T1), 1 g/L (T2), 1.5 g/L (T3), and 2 g/L (T4) and fed a 35% protein diet. After the 90-day trial, the physio-biochemical, molecular, and tissue-level changes were assessed. An integrated biomarker response (IBR) analysis for the key stress indicators aided us in better understanding them. There was a significant difference in blood count between T1 and T4 (total erythrocyte count, hemoglobin, and packed cell volume). T1 had higher levels of globulin and total plasma protein, but T2 had higher levels of albumin. Only in T1 did the respiratory burst and lysozyme activity appear to be higher (p < 0.05). Increased stocking densities had a significant impact on the liver function enzymes, GOT and GPT (p < 0.05). In comparison to lower densities (T1 & T2), higher stocking density (T3 & T4) was found to raise glucose and cortisol levels (p < 0.05). Antioxidant enzymes such as catalase, glutathione-S-transferase, and malondialdehyde were found to be more pronounced in lower density tissues (T1). Furthermore, the IBR plots show that lower densities have better health than higher densities. At higher stocking densities, mRNA expression of HSP70, IL-1, and IL-20 increased (p < 0.05) in kidney and liver tissues. The Nrf-2 and Tlr-9 genes were also upregulated. Also, when stocking density was increased, tissue-level histo-architectural changes were more pronounced than when stocking density was kept low. The findings of this study show that the welfare of Butter catfish cultured at high density in biofloc systems suffers from severe stress, and therefore draw more attention to the development of a species-specific standard rearing methodology in the pursuit of a profitable aqua-farming enterprise.

Abstract A 90‐day long indoor aquarium trial was conducted to assess the consequence of temperature on the growth, blood chemistry and histology of gill, intestine and liver tissues of Ompok bimaculatus juveniles. Homogeneous juveniles were randomly stocked into four different treatments of 20, 35 30 and 25℃ (room temperature as control), and these replications were marked as T20, T30, T35 and T25, respectively. Juvenile fish were fed with commercial diets at 5% body weight three consecutive times a day. Fish in T30 showed significantly higher growth performances and a higher percentage of specific growth rate (SGR%) in comparison to the control group in T25 (p 0.05) changes in SGR% were reported between T30 and T35 groups. Haematological analyses showed significant (p 0.05) in red blood cells (RBC) were observed between T25 and T30, while T20 and T35 showed significantly lower RBC. Histological analyses revealed that the liver and gill tissues were well‐shaped in T30 compared to distinctive pathology in other treatments. Again, the apparent formation of intestinal villi height was highest observed in T30 in comparison to other groups. It is concluded that the highest growth performance and physiological development of butter catfish would be obtained at 30℃ rearing temperatures.

Background: Butter catfish (Ompok bimaculatus) is a preferred species in South East Asia, with huge aquaculture potential. However, there is limited information about genetic stock composition due to insufficient markers. The goal of this study was to develop de novo microsatellite markers. Methods and results: For sequencing, genomic SMRT bell libraries (1.5 Kbp size) were prepared for O. bimaculatus. A total of 114 SSR containing sequences were used for primer designing. Polymorphic loci were validated by genotyping 83 individuals from four distant riverine populations, viz., Brahmaputra, Bichiya, Gomti and Kaveri. A total of 30 microsatellite loci were polymorphic, of which five were found to be associated with functional genes and eight (four positive and four negative) loci were found to be under selection pressure. A total of 115 alleles were detected in all loci and PIC ranged from 0.539 to 0.927 and pair-wise FST values from 0.1267 to 0.26002 (p < 0.001), with an overall FST value of 0.17047, indicating the presence of population sub-structure. Cross-species transferability of 29 loci (96.67%) was successful in congener species, Ompok pabda. Conclusion: The novel SSR markers developed in this study would facilitate stock characterization of natural populations, to be used in future selection breeding programs and planning conservation strategies in these species. Identified non-neutral markers will give insights into the effect of local adaptation on genetic differentiation in the natural population of this species. [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 butter catfish, Ompok bimaculatus, belonging to the silurid family, is widely regarded as an important food fish for aquaculture diversification in India. Furthermore, the species poses a threat due to habitat degradation and other anthropogenic factors, and has been categorised as "near threatened", therefore, its culture promotion is warranted. To establish a successful breeding programme, a precise understanding of the life history, and biology (reproductive/feeding) of the fish will assist hatchery managers and researchers. Studies in these areas have been undertaken by several groups over the years, but without much coherence, the data are still fragmented. Few attempts on the culture attributes of this catfish have been performed under both mono- and polyculture systems to bring about parallel promotion through aquaculture in a larger part of the subcontinent. Highlighting this, we have tried to analyse and present a consolidated account of the morphological characteristics, feeding habits, reproductive biology, early developmental ontogeny, and culture potentials of O. bimaculatus in India. This review was also prompted by the paucity of information on the cultural aspects of the species. Additionally, based on the reported studies, future directions and perspectives of the culture promotion of the species are proffered to ensure future research initiatives. [ABSTRACT FROM AUTHOR]

Thestudywasconductedinlaboratoryconditionstoevaluatetheeffectsofsalinityongrowth,survival,andbloodchemistryofbuttercatfish,Ompokbimaculatusfingerlings.Thefry,initiallysized as 7.01 cm length and 1.69 g weight, were assigned in four different salinity treatments i.e., 0 ppt (TC), 2 ppt (T1), 4 ppt (T2) and 8 ppt (T3) with three replications, with 21 fry in each replication as well. Fish were fed commercial catfish diets with 43% protein and 8% lipid at 5% body weight three times a day for 90 days. The control (TC) treatment showed the significantly highest growth perfor-mance among treatments, (p lt;0.05). The T3 treatment group showed a lethal parameter and all fish died within 72 hours of exposure to it. The survival rate was recorded as 90.47% for Tc, 71.43% for T1 and 47.61% for T2 treatment. The mean weight and length gain 6.17 g and 4.93 cm observed in T1 followed by 4.59 g and 3.06 cm in T2 treatment. The specific growth rate (SGR) (%) mean weight gain, length gain, average daily weight gain, average daily length gain and percentage length gain were (%) found to be significantly higher in Tc in comparison to those in the salinity treated groups (p lt;0.05).SignificantlyhigherhemoglobinandWBCwereobservedinTcamongtreatmentsandhad the lowest value recorded in T1 and T2. There were no significant changes between RBC counts among treatments.

Most of the adoption studies in catfish culture were restricted to feeding habits, growth rate and morphological studies, neglecting the social factors and adoption of phase-specific technologies (pre-stocking, stocking, and post-stocking) developed for the culture system. This study aims at assessing the extent of adoption of the scientific culture practices of Pabda (Ompok bimaculatus) fish in different phases (pre-stocking, stocking, and post-stocking) of culture and identifying the factors influencing the adoption behaviour. The study was conducted in ex-post-facto research design in Tripura, a northeastern state in India with 100 sample respondents, determined by Cochran's formula. The adoption behaviour was quantified with scores assigned 2 and 1 for full and partial adoption respectively, while 0 for discontinuance or rejection. An exploratory factor analysis model was administered to identify the factors. The study unfolds that experienced farmers (48%) had higher adoption levels, and young farmers (12%) were lesser involved. Adoption behaviour differs with phases of stocking at micro-level (district-wise) study with the indication of negligence in the stocking phase. Exploratory factor analysis identifies seven factors that formed the determinants of adoption behaviour of fish farmers and explained 55.97% of the variance. [ABSTRACT FROM AUTHOR]

The study was conducted in laboratory conditions to evaluate the effects of salinity on growth, survival, and blood chemistry of butter catfish, Ompok bimaculatus fingerlings. The fry, initially sized as 7.01 cm length and 1.69 g weight, were assigned in four different salinity treatments i.e., 0 ppt (TC), 2 ppt (T1), 4 ppt (T2) and 8 ppt (T3) with three replications, with 21 fry in each replication as well. Fish were fed commercial catfish diets with 43% protein and 8% lipid at 5% body weight three times a day for 90 days. The control (TC) treatment showed the significantly highest growth performance among treatments, (p<0.05). The T3 treatment group showed a lethal parameter and all fish died within 72 hours of exposure to it. The survival rate was recorded as 90.47% for Tc, 71.43% for T1 and 47.61% for T2 treatment. The mean weight and length gain 6.17 g and 4.93 cm observed in T1 followed by 4.59 g and 3.06 cm in T2 treatment. The specific growth rate (SGR) (%) mean weight gain, length gain, average daily weight gain, average daily length gain and percentage length gain were (%) found to be significantly higher in Tc in comparison to those in the salinity treated groups (p<0.05). Significantly higher hemoglobin and WBC were observed in Tc among treatments and had the lowest value recorded in T1 and T2. There were no significant changes between RBC counts among treatments. [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.

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) growth in relation to weight gain percentage (717.67 ± 39.10) and specific growth rate (1.14 ± 0.05). Survival percentage was also significantly higher (p < 0.01) at lower stocking densities compared with 35 fingerlings m-3. Similarly, the feed conversion efficiency (0.423 ± 0.025), protein efficiency ratio (1.37 ± 0.15) and feed conversion ratio (FCR) (2.37 ± 0.16) were significantly better at density of 15 fingerlings m-3. The fish growth and feed utilization efficiency did not vary significantly (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. [ABSTRACT FROM AUTHOR]

The Indian butter catfish, Ompok bimaculatus (Bloch, 1794), is a high-value catfish that has gained immense consumer preference in South-East Asia. However, information on the nutritional requirements of this species is scanty. Hence, an experiment was conducted to evaluate the effects of varying dietary lipid levels on growth, body composition, and activities of digestive and metabolic enzymes in larvae. Three isonitrogenous (40% crude protein) diets were formulated by supplementing fish and vegetable oil (1:1) at 4.5% (D1), 7% (D2), and 9.5% (D3) levels (containing crude lipid 5.7%, 8.0%, and 10.45%, respectively in diets D1-D3) to a fish meal- and oilcake-based formulated diet. Experimental diets were fed to butter catfish larvae (0.15 ± 0.01 g) in triplicate groups for a period of 42 days. Proximate compositions of the experimental diets, as well as fish carcass, were analyzed using standard procedures (AOAC 2005). Digestive and metabolic enzyme activities were analyzed at the completion of the experiment by standard methodology. Butter catfish larvae fed the diet D2 (8% crude lipid) resulted in the best performance in terms of weight gain (final weight 1.40 ± 0.07 g), net weight gain (1.31 ± 0.06 g), specific growth rate (5.50 ± 0.05% · day-1), and protein efficiency ratio (2.39 ± 0.17). The highest lipid deposition (2.90 ± 0.12%) in the carcass was also recorded in fish reared on diet D2. The final weight, net weight gain, protein efficiency ratio, and specific growth rate were significantly (P < 0.05) higher in D2 having 8% lipid. Moisture and lipid contents of the whole body were significantly (P < 0.05) higher in larvae fed diet D2. Amylase activity in fish significantly (P < 0.05) decreased with increasing dietary lipid levels. The maximum alkaline protease, pepsin, and lipase activities were noticed in the larvae fed diet D2. Progressive decrease in liver glucose-6-phosphate dehydrogenase activities and significant increase (P < 0.05) in the activities of neoglucogenic enzymes (glucose-6-phosphatase and fructose-1,6-bis phosphatase) were noticed with an increase in dietary lipid levels. Significantly lower (P < 0.05) activities of LDH, ALT, and AST were recorded in the group fed diet D2. Results of the study indicated that 8% crude lipid in the diet could assure optimum growth and survival of butter catfish larvae during early development. An appraisal on growth, body composition, and digestive as well as metabolic function in the butter catfish larvae recorded in the study might provide some important information to consider application of formulated diets for the larviculture of Ompok bimaculatus. [ABSTRACT FROM AUTHOR]

Abstract Objective Pabda (Ompok bimaculatus) is a freshwater catfish, largely available in Asian countries, especially in Bangladesh, India, Pakistan and Nepal. This fish is highly valued for its fabulous taste and high nutritional value and is very popular as a rich source of proteins, omega-3 and omega-6 fatty acids, vitamins and mineral for growing children, pregnant females and elders. We performed de-novo sequencing of Ompok bimaculatus using a hybrid approach and present here a draft assembly for this species for the first time. Data Description The genome of Ompok bimaculatus (Fig. 1: Table 1, Data file 3) from Ganges river, has been sequenced by hybrid approach using Illumina short reads and PacBio long reads followed by structural annotations. The draft genome assembly was found to be 718 Mb with N50 size of 81 kb. MAKER gene annotation tool predicted 21,371 genes.

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]

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]

The genus Gangesia Woodland, 1924 contains 8 valid species. Gangesia pashupatii sp.n. from the intestine of a freshwater fish Wallago attu from Canning, South 24-Parganas, West Bengal, India and Gangesia puriensis sp.n. from Ompok bimaculatus from Puri in Odhisa, India are described and illustrated. Gangesia pashupatii sp.n. is characterized by presence of a rostellum that bears 50 hooks in two alternate rows; each hook 0.078 long; neck absent; testes 100-160 in number; and a uterus with 20-23 lateral diverticulae on each side. Gangesia puriensis sp.n. is characterized by an oval to bulbous scolex; rostellar hooks 28-29 in number all alike arranged in a single row; suckers without spines; long neck; testes 200-250 in number; long cirrus sac and uterus with 15-16 lateral diverticulae on each side. The presence of these new morphological characters differentiates the two observed new species from the rest of the described valid species in the genus. [ABSTRACT FROM AUTHOR]

The present study examined the gonadosomatic index (GSI), oocyte diameter (OD), ovarian morphology and histology of freshwater butter catfish Ompok bimaculatus from Gomati river, India. For the annual cycle study, monthly samples were collected from the Gomati river. The GSI increased with the progressively maturation of gonad. It increased significantly in July (4.98±0.047) and it reached its peak point in the month of August (5.37±0.037) and lowest value was observed in October month (0.64±0.019). The OD varied from 0.052±0.005 to 0.84±0.024; the maximum OD was observed in August month and lowest was observed in September month. It showed a significant relationship with GSI. Histological studies of ovary of O. bimaculatus revealed eight stages in oocyte development (oogonia, chromatin nucleolus, early perinucleolus, late perinucleolus, yolk vesicle, vitellogenesis, vitellogenic and post ovulatory follicles). The month wise studies of different parameters helped in confirming annual cycle as; resting phase (November-February), preparatory phase (March-April), pre-spawning phase (May- June), spawning phase (July-August) and post-spawning phase (September-October). These observations are important for a better understanding of reproductive biology of this fish in northern region to adopt breeding practices of female Ompok bimaculatus. [ABSTRACT FROM AUTHOR]

The silurid butter catfish, Ompok bimaculatus (Bloch, 1794), is widely distributed in the plains and sub-mountain regions of India, but not enough is known about its reproductive potential is still insufficient. The present study evaluated the comparative reproductive potential (in terms of sex ratio, spawning season, body size at first go­nadal maturity, gonadosomatic index, fecundity, egg dimension, egg weight etc.) of fish (n=1223) from six tropical tributaries of the Ganges basin during January 2011-December 2013. The females had relatively greater weight and length. The body size at 50% first gonadal matu­rity (L50%) ranged between 228-262mm in females and 198-247mm in males. The population has high and low fecundities. The correlations between absolute fecundity and total length, as well as between body weight and gonad weight, were significant (p

Documentation of genetic differentiation among the populations of a species can provide useful information that has roles in conservation, breeding, and management plans. In the present study, we examined the genetic structure and phylogenetic relationships among the 149 individuals of Ompok bimaculatus belonging to 24 populations, collected from Indian waters, using cytochrome b gene. The combined analyses of data suggested that the Indian O. bimaculatus consist of three distinct mtDNA lineages with star-like haplotypes network, which exhibited high genetic variation and haplotypic diversity. Analysis of molecular variance indicated that most of the observed genetic variation was found among the populations suggesting restricted gene flow. Long-term interruption of gene flow was also evidenced by high overall Fst values (0.82367) that could be favored by the discontinuous distributions of the lineages. [ABSTRACT FROM AUTHOR]

Scientific research into fish wellness is critical, and the concerns about crowding-related stress due to increased stocking density are inevitable. Taking this into consideration, the study defines the physiological signature of Ompok bimaculatus (Butter catfish) in a biofloc system when subjected to varying levels of stocking density. Fish (mean weight = 1.21  g  ± 0.08, n  = 600) were randomly stocked in 40-L glass aquaria at stocking densities of 0.5 g/L (T1), 1 g/L (T2), 1.5 g/L (T3), and 2 g/L (T4) and fed a 35% protein diet. After the 90-day trial, the physio-biochemical, molecular, and tissue-level changes were assessed. An integrated biomarker response (IBR) analysis for the key stress indicators aided us in better understanding them. There was a significant difference in blood count between T1 and T4 (total erythrocyte count, hemoglobin, and packed cell volume). T1 had higher levels of globulin and total plasma protein, but T2 had higher levels of albumin. Only in T1 did the respiratory burst and lysozyme activity appear to be higher (p < 0.05). Increased stocking densities had a significant impact on the liver function enzymes, GOT and GPT (p < 0.05). In comparison to lower densities (T1 & T2), higher stocking density (T3 & T4) was found to raise glucose and cortisol levels (p < 0.05). Antioxidant enzymes such as catalase, glutathione-S-transferase, and malondialdehyde were found to be more pronounced in lower density tissues (T1). Furthermore, the IBR plots show that lower densities have better health than higher densities. At higher stocking densities, mRNA expression of HSP70 , IL-1, and IL-20 increased (p < 0.05) in kidney and liver tissues. The Nrf-2 and Tlr-9 genes were also upregulated. Also, when stocking density was increased, tissue-level histo-architectural changes were more pronounced than when stocking density was kept low. The findings of this study show that the welfare of Butter catfish cultured at high density in biofloc systems suffers from severe stress, and therefore draw more attention to the development of a species-specific standard rearing methodology in the pursuit of a profitable aqua-farming enterprise., Competing Interests: No potential conflicts of interest were reported by the authors., (© 2023 The Authors. Published by Elsevier Ltd.)

Objective: Pabda (Ompok bimaculatus) is a freshwater catfish, largely available in Asian countries, especially in Bangladesh, India, Pakistan and Nepal. This fish is highly valued for its fabulous taste and high nutritional value and is very popular as a rich source of proteins, omega-3 and omega-6 fatty acids, vitamins and mineral for growing children, pregnant females and elders. We performed de-novo sequencing of Ompok bimaculatus using a hybrid approach and present here a draft assembly for this species for the first time. Data Description: The genome of Ompok bimaculatus (Fig. 1: Table 1, Data file 3) from Ganges river, has been sequenced by hybrid approach using Illumina short reads and PacBio long reads followed by structural annotations. The draft genome assembly was found to be 718 Mb with N50 size of 81 kb. MAKER gene annotation tool predicted 21,371 genes. [ABSTRACT FROM AUTHOR]

Growth, survival and production of endangered Indian butter catfish ( Ompok bimaculatus) fingerlings were examined at different stocking densities. The experiment was conducted for 8 months in nine earthen ponds having an area of 0.03 ha each. 30-day-old fingerling, stocked at 40 000 ha−1 was designated as treatment-1 (T1), 50 000 ha−1 as treatment-2 (T2) and 60 000 ha−1 as treatment-3 (T3). At stocking, all fingerlings were of same age group with a mean length and weight of 3.36 ± 0.08 cm and weight of 0.83 ± 0.02 g respectively. Fish in all the treatments were fed with a mixture of rice bran (50%), mustard oil cake (30%), fish meal (19%) and vitamin-mineral premix (1%). Physicochemical parameters, plankton populations and soil parameters were at the optimum level for fish culture. Highest weight gain was observed in T1 and lowest in T3. Final length, weight and survival of fish also followed the same trend as weight gain. Highest specific growth rate was observed in T1 followed by T2 and T3. Feed conversion ratio was significantly lower in T1 followed by T2 and T3 in that order. Significantly higher amount of fish was produced in T1 than T2 and T3 respectively. Higher net benefit was obtained from T1 than from T2 and T3. Overall, the highest growth, survival and benefit of fish were obtained at a density of 40 000 fingerlings ha−1. Hence, of the three stocking densities, 40 000 fingerlings ha−1 appears to be the most suitable stocking density for culturing of Indian butter catfish in grow-out system. [ABSTRACT FROM AUTHOR]

Ompok bimaculatus commonly called as Indian butter catfish is a commercially important food fish and distributed throughout India and Southeast Asia. Genetic differentiation of O. bimaculatus was investigated using cytochrome b (cyt b) gene of three different riverine populations. A total of 37 sequences of cyt b gene (1118 bp) were generated from O. bimaculatus. The mitochondrial DNA analysis revealed that O. bimaculatus has relatively high genetic diversity. The estimated haplotype and nucleotide diversity were 0.063 and 0.005, respectively. The analysis of molecular variance indicated 73.53% genetic variability between the populations and 26.47% genetic variation within population. The understanding of genetic differentiation of O. bimaculatus populations will play a key role in conservation and management of the important endangered fish species. [ABSTRACT FROM AUTHOR]