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Rohu ( Labeo rohita ) is a major aquaculture species in Bangladesh, but poor broodstock management has compromised seed quality and growth performance. To address this, WorldFish launched a genetic improvement program in 2012, yet the on‐farm performance of the widely available third generation (G3) rohu remains poorly studied. This study aimed to evaluate and compare the growth and profitability of G3 rohu and commercial local rohu under typical smallholder pond polyculture systems in Bangladesh. A total of 120 ponds across two locations were randomly assigned to Selected (30 per location, G3 rohu) or Control (30 per location, local rohu), with rohu stocked at an average of 2470 ha −1 in typical smallholder polyculture systems alongside 5287 ha −1 of other cocultured species. The study was conducted over a full production cycle from July 2023 to March 2024, and differences in performance were assessed using multivariate regression and ANOVA models. Water quality remained within acceptable ranges for aquaculture, despite fluctuations. The Selected rohu demonstrated significantly higher ( p ≤ 0.05) harvest weight, weight gain, survival rate, and specific growth rate (SGR), growing 32.6% faster than Control rohu. Productivity of cocultured species did not differ significantly ( p ≥ 0.05) between ponds with Selected or Control rohu. Furthermore, G3 rohu yielded significantly higher returns per ha than local rohu, with total productivity, gross revenue, gross margin, net margin, and benefit–cost ratios (BCRs) all significantly higher ( p ≤ 0.05) in ponds with Selected rohu. Regression analysis identified pond size, commercial feed use, inorganic fertilization, and stocking density as positive drivers of rohu productivity, whereas pond age had negative effects. Findings are based on data from two districts in southern Bangladesh and may vary elsewhere depending on local farming intensity and management practices. These results suggest that wider dissemination of genetically improved fingerlings, coupled with improved pond management, could enhance smallholder productivity and profitability in Bangladesh.

The impact of rohu swim bladder gelatin hydrolysate (SBGH) at different levels on textural, sensory, oxidative, and microbial properties of polyunsaturated fatty acids enriched rohu fish cooked sausages (PUFA-RFS) were investigated in the current study. SBGH addition enhanced the lightness values of PUFA-RFS compared to both control sausages (without SBGH and with butylated hydroxyanisole (BHA) (P > 0.05). PUFA-RFS added with 3% SBGH exhibited higher hardness, cohesiveness, and gumminess throughout the storage duration at both 4 °C and −20 °C temperatures when compared to other sausages counterparts. PUFA-RFS added with SBGH displayed lower PV, TBARS, and total microbial counts than the control sausages. Furthermore, PV, TBARS, and total microbial count values of sausage decreased with an increase in SBGH level, indicating retardation in lipid oxidation and microbial growth by SBGH in a dose-depended manner. Nevertheless, sausage added with 3% SBGH had higher overall acceptability than other sausage counterparts. Therefore, SBGH could retard lipid oxidation and improves textural properties of PUFA-enriched fish sausage.

Salinity is a critical abiotic factor in aquatic environments imposing severe stress on farmed freshwater species, and negatively impacting growth, metabolism, immunity, and overall wellbeing. The Indian major carp, rohu ( Labeo rohita ) has been facing various production-related issues associated with salinity intrusion in the upper coastal regions of Bangladesh. The current study examined the effects of four different salinity levels (0‰ as control, 2‰, 4‰, and 6‰) on selected cellular (ultra-structure of gill), physiological, biochemical, and gene expression traits of rohu. Experimental salinity levels significantly affected different biological parameters of rohu ( P  < 0.05) including moderate to severe levels of gill tissue damage, 16–25% slower growth, 12–30% lower survival, and a 15–56% higher O 2 consumption for the treatment groups (2‰, 4‰, and 6‰) when compared to the control (0‰). Blood glucose (≈55 µg/ml for control while 76–128 µg/ml for the treatments) and stress hormone (cortisol) levels (≈75 ng/ml for control and 87–145 ng/ml for the salinity treatments) increased with increasing salinity levels whereas blood cell counts were in a declining trend (23 × 10 6 to 17 × 10 6 cells/µl). Expression levels of the six selected genes showed salinity-specific differential changes; 1.5 to 2 - fold higher expression of growth, immunity, and metabolic genes were observed for control conditions while the ion regulatory genes showed 2 to 3 fold higher expression levels for the salinity treatments (2‰, 4‰, and 6‰) compared to the control. Results of this study indicate that different salinity levels impose stress at varying orders of magnitude on experimental rohu. It was also evident that rohu deploys different biological responses to cope with the rising salinity. Therefore, this study provides important clues to develop salinity tolerant lines/strains of rohu that may help to reduce potential adverse effects related to climate change (i.e., inland salinity intrusion) on the farming of this species.

Medicinal herbs are known for their diverse immunomodulatory properties, with bioactive compounds making them potential immunoadjuvants in vaccination. This study investigated the immunoadjuvant potential of ethanolic root extract from Asparagus racemosus (AREE) in rohu ( Labeo rohita ) fingerlings, using a formalin-killed Aeromonas hydrophila vaccine. A total of 360 rohu fingerlings were randomly divided into six groups, each with three replicate tanks. The fish were immunized via intraperitoneal injection with one of the following: phosphate-buffered saline (PBS), bacterin (B), bacterin combined with AREE (B + AREE), bacterin mixed with Freund’s complete adjuvant (B + FCA), FCA alone, or AREE alone. Serum, head kidney leucocytes, and head kidney tissues were collected 30 days post-immunization to assess antibody titers, antigen-specific leucocyte proliferation, and expression of immune genes (IL-1β, IFN-γ, IL-2, IgM, and IgT). Thirty days after immunization, ten fish from each group were challenged with A. hydrophila , and mortality was monitored for 2 weeks to calculate survivability. The B + AREE and B + FCA groups exhibited significantly higher ( P  ≤ 0.05) antibody titers, leucocyte proliferation, and immune gene expression compared to other groups. The post-immunization challenge revealed a significantly higher ( P  ≤ 0.05) survivability rate in the B + AREE (66.67 ± 3.33%) and B + FCA (70 ± 5.77%) groups. These findings suggest that AREE can serve as an effective immunoadjuvant with A. hydrophila bacterin, offering similar protection to Freund’s complete adjuvant in rohu against A. hydrophila infection.

IntroductionNannochloropsis oceanica CASA CC201 is a marine microalga valued for its capacity to accumulate high levels of polyunsaturated fatty acids, particularly essential omega-3 fatty acid EPA. In carp nursery culture, low survival rates from spawn to fry (25–30%) and from fry to fingerling (40–50%) are often attributed to inadequate access to easily digestible, high-quality nutrients. This study evaluated the potential of N. oceanica–derived algae oil as a sustainable dietary lipid source to improve growth, survival, immune responses, and gut enzymatic activity in nursery-reared rohu (Labeo rohita).MethodsA three-week feeding trial was conducted using four iso-nitrogenous and iso-lipidic diets formulated with fish oil (FO), N. oceanica algae oil (AO), linseed oil (LO), or sunflower oil (SFO). Each diet was randomly assigned to triplicate groups across 12 indoor nursery tanks (2000 L), with 2000 rohu spawn stocked per tank in a completely randomized design. Fish were fed twice daily, aeration was maintained continuously, and weekly water renewal ensured optimal water quality. Growth performance, survival, non-specific immunity parameters (lysozyme, haemolytic, haemagglutination, and myeloperoxidase activities), and digestive enzyme activities (amylase, protease, and lipase) were assessed at the end of the experiment.ResultsThe AO diet resulted in the highest survival among nursery rohu, while the FO diet produced the greatest growth performance. Gut enzyme analysis indicated the highest amylase activity in fish fed FO and the highest lipase activity in fish fed AO, with protease showing no marked trend among treatments. No significant differences were detected in non-specific immune parameters across dietary groups.DiscussionAlgae oil derived from N. oceanica demonstrated clear advantages in enhancing survival and lipase activity, outperforming conventional plant oils and offering a viable partial or complete replacement for fish oil in nursery diets. Although FO supported superior growth, AO provided a more sustainable alternative that could improve overall nursery performance without compromising immunity. These findings underscore the potential of microalgal oils as functional and eco-friendly lipid sources for early-stage carp aquaculture.

Aeromonas hydrophila is a Gram-negative bacterium that causes high mortality in different fish species and at different growth stages. Although vaccination has significantly contributed to the decline of disease outbreaks in aquaculture, the use of oral vaccines has lagged behind the injectable vaccines due to lack of proven efficacy, that being from primary immunization or by use of boost protocols. In this study, the outer membrane protein W (OmpW) of A. hydrophila was cloned, purified, and encapsulated in poly d,l-lactide-co-glycolic acid (PLGA) nanoparticles (NPs) for oral vaccination of rohu (Labeo rohita Hamilton). The physical properties of PLGA NPs encapsulating the recombinant OmpW (rOmpW) was characterized as having a diameter of 370–375 nm, encapsulation efficiency of 53% and −19.3 mV zeta potential. In vitro release of rOmpW was estimated at 34% within 48 h of incubation in phosphate-buffered saline. To evaluate the efficacy of the NP-rOmpW oral vaccine, two antigen doses were orally administered in rohu with a high antigen (HiAg) dose that had twice the amount of antigens compared to the low antigen (LoAg) dose. Antibody levels obtained after vaccination showed an antigen dose dependency in which fish from the HiAg group had higher antibody levels than those from the LoAg group. The antibody levels corresponded with post challenge survival proportions (PCSPs) and relative percent survival (RPS) in which the HiAg group had a higher PCSP and RPS than the LoAg group. Likewise, the ability to inhibit A. hydrophila growth on trypticase soy agar (TSA) by sera obtained from the HiAg group was higher than that from the LoAg group. Overall, data presented here shows that OmpW orally administered using PLGA NPs is protective against A. hydrophila infection with the level of protective immunity induced by oral vaccination being antigen dose-dependent. Future studies should seek to optimize the antigen dose and duration of oral immunization in rohu in order to induce the highest protection in vaccinated fish.

Labeo rohita (rohu) is a carp important to aquaculture in South Asia, with a production volume close to Atlantic salmon. While genetic improvements to rohu are ongoing, the genomic methods commonly used in other aquaculture improvement programs have historically been precluded in rohu, partially due to the lack of a high-quality reference genome. Here we present a high-quality de novo genome produced using a combination of next-generation sequencing technologies, resulting in a 946 Mb genome consisting of 25 chromosomes and 2,844 unplaced scaffolds. Notably, while approximately half the size of the existing genome sequence, our genome represents 97.9% of the genome size newly estimated here using flow cytometry. Sequencing from 120 individuals was used in conjunction with this genome to predict the population structure, diversity, and divergence in three major rivers (Jamuna, Padma, and Halda), in addition to infer a likely sex determination mechism in rohu. These results demonstrate the utility of the new rohu genome in modernizing some aspects of rohu genetic improvement programs.

The present study focused on preparing rohu egg sauce using optimized conditions through enzymatic and fermentative methods. The enzymatic preparation of rohu egg sauce (ERS) involved homogenizing the eggs in water at a ratio of 1:0.9 (w/v), followed by the addition of salt (20% w/w) and papain (3% w/w). A mixture containing salt (25% w/w), sugar (7.5% w/w), and inoculum (10% (w/v)) of Pediococcus pentosaceus FSBP4-40 was utilized to prepare fermentatively produced rohu egg sauce (FRS). ERS and FRS were then stored at room temperature (25 ± 2 °C) and 37 °C for 180 days. After storage, both sauces were evaluated for their scavenging activity against DPPH, ABTS, and superoxide anion (SOA). The ERS demonstrated significantly higher DPPH, ABTS, and SOA scavenging activity compared to the FRS, with values of 61.61 ± 7.33%, 71.21 ± 2.14%, and 85.11 ± 4.92%, respectively, as opposed to 37.49 ± 5.34, 52.31 ± 1.76%, and 63.09 ± 2.31%. Significant changes were observed in the fatty acid profile of the sauces during 180 day storage. Furthermore, after 180 days, the bacterial counts in the FRS were much lower than in the ERS. Overall, this study highlights the importance of using enzymes and LAB in accelerating the hydrolytic process to produce biofunctional rohu egg sauce.

Abstract We have evaluated the effects of different fish feeds on the body composition, growth, and enzyme activities of Labeo rohita (Rohu). In total, 240 fishes between the average weights of 24.77±2.15g were studied. The treatments were applied in a completely randomized design, with 4 treatments of 60 fishes each. Treatments consisted of four different fish feeds [Oryza (T1), AMG (T2), Aqua (T3), and Supreme (T4)]. Body composition, growth performance, and enzyme activities were evaluated. There was a significant variation in performance of fishes fed with different type of feed; as fishes having Oryza feed showed the highest weight gain, specific growth rate (SGR), and best feed conversion ratio (FCR) as compared to other groups that were considered to be significant (P ≤ 0.05). High net weight gain was obtained in T4 when compared with T2 and T3. FCR value of T4 was less than T1 but higher than T2, T3 and T2, which showed the lowest values. The specific growth rate was recorded as average in T4, but T2 led a high SGR than T3. Similarly, crude protein level and digestive enzymes activity was recorded significantly highest in fed with Oryza (T1) as compared to AMG (T2), Aqua (T3), and Supreme (T4). Water quality parameters were recorded significant in all treatments except pH and DO of treatment (T1), significantly different from other treatments. It was concluded that Rohu (Labeo rohita) could show a promising growth rate and protease enzyme activity when fed with the Oryza feed of 25% protein. Resumo Avaliamos os efeitos de diferentes alimentos para peixes em relação à composição corporal, crescimento e atividades enzimáticas de Labeo rohita (Rohu). No total, foram estudados 240 peixes com pesos médios de 24,77 ± 2,15 g. Os tratamentos foram aplicados em delineamento inteiramente casualizado, com quatro tratamentos de 60 peixes cada. Os tratamentos consistiram em quatro alimentos diferentes para peixes: Oryza (T1), AMG (T2), Aqua (T3) e Supreme (T4). Foram avaliados a composição corporal, o desempenho de crescimento e as atividades enzimáticas. Houve uma variação significativa no desempenho dos peixes alimentados com diferentes tipos de ração. Peixes com alimentação Oryza apresentaram maior ganho de peso, taxa de crescimento específico (SGR) e melhor taxa de conversão alimentar (FCR) em comparação com outros grupos que foram considerados significativos (P ≤ 0,05). Elevado ganho de peso líquido foi obtido em T4 quando comparado com T2 e T3. O valor da FCR de T4 foi menor que T1, mas maior que T2 e T3, que apresentaram os menores valores. A taxa de crescimento específico foi registrada como média em T4, mas T2 teve uma SGR alta do que T3. Da mesma forma, o nível de proteína bruta e a atividade das enzimas digestivas foram registrados significativamente mais altos nos peixes alimentados com Oryza (T1) em comparação com AMG (T2), Aqua (T3) e Supreme (T4). Os parâmetros de qualidade da água foram registrados como significativos em todos os tratamentos, exceto pH e OD do tratamento (T1), significativamente diferente dos demais tratamentos. Concluiu-se que Rohu (Labeo rohita) pode apresentar uma taxa de crescimento promissora e atividade da enzima protease quando alimentado com Oryza de 25% de proteína.