Journal of Fisheries

Immunomodulatory effects of indigenous herbal feed additives on innate immunity of common carp (Cyprinus carpio) challenged with Aeromonas hydrophila

2026-07-14T20:40:45+00:00

The increasing incidence of bacterial diseases in aquaculture necessitates the development of sustainable immunostimulatory strategies as alternatives to antibiotics. The present study evaluated the immunomodulatory and growth-promoting effects of indigenous herbal feed additives on common carp (Cyprinus carpio) challenged with Aeromonas hydrophila. Fish were fed diets supplemented with neem (Azadirachta indica), tulsi (Ocimum sanctum), and their combination for 90 days under controlled conditions, followed by bacterial challenge. Hematological parameters, including hemoglobin (Hb), red blood cell (RBC) count, total leukocyte count (TLC), and packed cell volume (PCV), along with growth indices such as specific growth rate (SGR), weight gain, and feed conversion ratio (FCR), were evaluated. Results showed a significant improvement in hematological and immune parameters in all treated groups compared to control, with the combined supplementation (neem + tulsi) exhibiting the most pronounced effects. The highest Hb, RBC, TLC, and PCV values were observed in the combination group, indicating improved oxygen transport capacity and immune competence. Growth performance was also significantly improved, as indicated by higher SGR and weight gain and lower FCR. Following bacterial challenge, treated groups exhibited increased resistance and survival, confirming the protective role of herbal supplementation. The findings demonstrate that dietary inclusion of indigenous herbal additives, particularly in combination, effectively enhances innate immunity, hematological health, and growth performance in common carp (Cyprinus carpio). This study highlights the potential of phytogenic feed additives as eco-friendly and sustainable alternatives for disease management in aquaculture systems.

Formulation and characterization of Halymenia dilatata-based nori alternative through nutritional, sensory, structural, textural, and functional analyses

2026-07-14T18:58:25+00:00

The increasing demand for seaweed-based foods has created interest in developing sustainable alternatives to conventional Porphyra-based nori using tropical seaweed resources. This study developed a nori-like product from Halymenia dilatata and evaluated the effects of glycerin concentration and drying conditions on its nutritional, physicochemical, structural, and sensory properties. Four formulations were prepared using a constant seaweed-to-water ratio (1:10, w/v) with varying glycerin concentrations. The formulation containing 2.5% glycerin and dried at 55°C for 2 h produced sheets with the best pliability, uniformity, and handling characteristics. The optimized product contained low moisture (7.84%), moderate protein (11.62%), high dietary fibre (31.54%), and a mineral-rich ash content (14.87%), with appreciable levels of iron and zinc and a balanced sodium-to-potassium ratio. Sensory evaluation indicated good consumer acceptance for appearance, flavour, texture, and overall acceptability. Structural analyses confirmed the formation of a cohesive polysaccharide network, while biochemical and microbiological analyses demonstrated favourable quality, oxidative stability, and microbial safety. These findings demonstrated that H. dilatata could be successfully developed into a nutritious, safe, and acceptable nori-like product with physicochemical characteristics comparable to those of conventional nori, highlighting its potential as a sustainable tropical alternative for value-added seaweed-based food products.

Age and growth of Oreochromis niloticus in the Samandéni Reservoir, Burkina Faso: a scale-based study

2026-07-14T08:26:26+00:00

Oreochromis niloticus is a key species supporting inland fisheries in tropical African reservoirs, including the recently impounded Samandéni Reservoir in Burkina Faso. However, age-based information required for reliable stock assessment remains limited for this reservoir. This study estimated age structure, growth parameters, and population characteristics of O. niloticus using scale readings from 318 specimens collected monthly between October 2021 and September 2022 at three sampling sites: Badoville (n = 114), Sadina (n = 100), and Dioufoulma (n = 104). Monthly sample sizes were relatively uniform, ranging from 25 to 28 individuals, ensuring consistent temporal coverage throughout the study period. Scale annuli were examined and validated using marginal increment analysis. The population exhibited a unimodal length-frequency distribution ranging from 10.0 to 32.0 cm (mean±SD: 20.38±0.17 cm). The sex ratio was significantly male-biased (2.06:1, χ² = 38.04, p < 0.001). Length–weight relationships indicated isometric growth for the pooled population (b = 2.96), negative allometry in males (b = 2.92), and isometric growth in females (b = 3.09). Marginal increment analysis confirmed annual annulus formation, with minimum values occurring in February during the dry season. The von Bertalanffy growth model showed rapid juvenile growth followed by a progressive decline after maturation. Age classes ranged from 0+ to VI+, with dominance of intermediate age groups (II+ to IV+), suggesting continuous recruitment and moderate exploitation pressure. These results provide the first validated scale-based age and growth parameters for O. niloticus in the Samandéni Reservoir and contribute essential baseline information for sustainable fisheries management.

The impact of 4-nonylphenol on the expression of the vitellogenin gene and the alterations in steroid hormones in male Sobaity seabream (Sparidentex hasta)

2026-07-14T08:26:38+00:00

The study aimed to investigate the effects of 4-nonylphenol exposure on the expression of the vitellogenin gene (Vg) and sexual steroid hormones in male Sobaity seabream (Sparidentex hasta). A total of 78 fish individuals were randomly assigned to six tanks, receiving doses of 10, 50, and 100 µg g^–1 of 4-nonylphenol, as well as 2 µg g^–1 of 17β-estradiol (E2) via intraperitoneal injection. The negative control group received a solvent mixture (ethanol and olive oil) with no injections. Fish sampling for blood and liver analysis occurred on days 0, 7, and 14. After RNA extraction from liver tissue and cDNA synthesis, variations in Vg expression were analyzed in relation to the beta-actin gene. The results showed a significant increase in Vg expression in the treatment groups compared to control groups. Sequencing confirmed the presence of the Vg gene, with a fragment size of 174 nucleotides. Additionally, plasma levels of sexual steroid hormones were measured using radiomonoactivity, which revealed a decrease in testosterone levels associated with varying concentrations of 4-nonylphenol. In contrast, E2 levels in fish exposed to 4-nonylphenol increased after 7 and 14 days. The findings suggest that exposure to 4-nonylphenol activates Vg production, potentially adversely affecting puberty, sexual development, sexual behaviors, and reproductive success in Sobaity seabream.

Comparative assessment of microplastics in Pulicat Lagoon and adjacent coastal waters: an integrated multi-metric ecological risk evaluation

2026-07-14T08:26:49+00:00

Microplastics (MP) have emerged as one of the most persistent contaminants in aquatic habitats, infiltrating even the most ecologically sensitive systems, such as lagoons and coastal waters, where ongoing anthropogenic inputs exacerbate their accumulation and biological impact. Pulicat Lake, India's second-largest brackish water lagoon, is especially vulnerable to MP loading from tidal exchange, household waste, and fishing activities. This study examined the physicochemical properties, seasonal abundance, and ecological danger of MP at three typical stations: Goonankuppam (Station I), Thonirevu (Station II), and Pulicat Beach (Station III) from 2024 to 2025. MP abundance ranged from 50 to 135 particles L^–1, peaking in Thonirevu during post-monsoon. This pattern was driven by accelerated monsoon runoff and water resuspension in the aftermath of cyclone Fengal (25 November 2024). Fibres (50.9% at Station I, 40.6% at Station II, and 51.1% at Station III) were the dominating morphotype, followed by fragments (22.60% at Station I, 27.40% at Station II, and 24.20% at Station III). The size fraction of 100–500 µm (56% at Station I, 49% at Station II, and 47% at Station III) was consistent across all locations, indicating advanced secondary fragmentation. Blue particles (40% at Station I, 30% at Station II, and 45% at Station III) predominated, highlighting the important role of fishing gear and maritime activities. This establishes a strong baseline for targeted mitigation in this ecologically sensitive lagoon-coastal interface.