Journal of Fisheries

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

2026-07-01T20:57:54+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

2026-07-01T18:08:15+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.

Setting exploitation reference points for the reba carp Cirrhinus reba in a snow-fed river: study from the Saryu River ecosystem in northern India

2026-07-01T08:20:34+00:00

This study examined length-weight relationships (LWRs), physiological condition, growth characteristics, recruitment pattern, probability of capture, mortality rates and exploitation status of Cirrhinus reba from the Saryu River of northern India, collected fortnightly from August 2024 to July 2025. Total length varied from 11.0 to 27.0 cm (17.974±0.142 cm), while body weight varied between 13.0 and 264.1 g (73.080±6.928 g). The LWR showed a strong correlation (r² ≥ 0.915). The Fulton’s condition factor (K_f) and relative condition factor (K_n) ranged from 1.133±0.134 to 1.366±0.237 and 0.832±0.143 to 2.025±0.23 respectively, which indicated that the fish were healthy. Growth parameters estimated through von Bertalanffy model were L_∞ = 27.0 cm, K = 0.65 year⁻¹ and Φ′ = 2.67. Recruitment occurred throughout the year with a major peak during the monsoon season. Total mortality, natural mortality and fishing mortality were estimated as 1.60, 0.73 and 0.87 year⁻¹, respectively. The probability of capture analysis indicated that the length at first capture L₅₀ of C. reba was 15.5 cm. The exploitation rate (E) 0.55 was higher than E_opt (0.50) indicating emerging overexploitation. Yield-per-recruit analysis indicated exploitation reference points of E_max as 0.62 and E_0.1 as 0.48. Virtual Population Analysis revealed increasing fishing mortality with fish size, with the highest fishing mortality (F = 0.91 year⁻¹) recorded in larger individuals, indicating size-selective exploitation and potential pressure on stock sustainability. This study provides information on population and exploitation characteristics of C. reba in the Saryu River, which can be used to set reference points for sustainable fisheries management.

Alterations in Nile tilapia Oreochromis niloticus erythrometry as sensitive indicators of dietary fluoroquinolone antibiotic enrofloxacin toxicity

2026-07-01T08:20:45+00:00

The use of antibiotics in aquaculture poses significant health risks to fish and consumers. Adopting and validating a standard, non-lethal, and cost-effective method to monitor fish health is essential. This study investigated the impact of fluoroquinolone antibiotic enrofloxacin (ENF) on the erythrocyte cellular and nuclear morphometric anomalies in Oreochromis niloticus. Fish were fed graded doses of ENF at 0 mg, 10 mg, 30 mg, 50 mg and 100 mg kg biomass^–1 day^–1 for 15 consecutive days, followed by a 21-day post-dosing observation. The results revealed significant alterations in erythrocyte morphometric characteristics, such as major and minor axes, volume, surface area, cell to nucleus ratio, and surface area to volume ratio due to dietary ENF, indicating its cytotoxicity and perilous effects on fish erythrocytes. The nucleus was shrinking more significantly than the cell under treatment-induced stress. On day 15 of dosing, the surface area to volume ratio increased in the dosing groups, except for the 10× group, which represented an adaptive response in the fish to facilitate greater area for gas exchange to occur. However, the observed dose- and time-dependent erythro-morphometry was reversible once dosing was suspended. The results showed that fish erythrometric abnormalities, a relatively unexplored area of clinical science, can serve as important biomarkers or sensitive indicators of toxicity of veterinary medicinal products in assessing the physiological health status of cultured aquatic organisms.

Effects of photoperiod on growth and ovarian maturation in female green mud crab, Scylla serrata (Forsskål, 1775)

2026-07-01T08:20:56+00:00

Photoperiod is one of the most significant environmental cues for an organism, which are also essential for controlling its growth, metabolism, and maturity. The current study used an 8-week experiment to examine the effects of photoperiod T1 (12L∶12D), T2 (18L∶6D), and T3 (6L∶18D) on mud crab (Scylla serrata) growth performance and gonadal maturation. A total of 36 healthy crabs (average initial weight 416.18±2.42 g) were fed twice daily at 10% of body weight. Crabs cultured under 6L∶18D (T3) showed the highest final weight (486.54±4.44 g), weight gain (70.45±3.92 g), specific growth rate (0.26±0.01 % day^–¹), gonadosomatic index (12.06±0.20%), and hepatosomatic index (5.64±0.35%), significantly higher than T1 and T2. Digestive enzyme activities (amylase, protease, lipase) were highest in the 6L∶18D group, indicating efficient nutrient utilization. Ovarian carotenoid levels were significantly (p < 0.05) higher in 6L∶18D (0.4399±0.0640 µg mg^–1). Histology revealed advanced vitellogenesis and a healthy hepatopancreas in the 6L∶18D group, while the 18L∶6D showed delayed maturation. Overall, the results indicate that among the treatment groups, the 6L∶18D improved the growth, digestion, and reproductive performance of female S. serrata. This could be used in broodstock maturation, which has a detrimental effect on wild stock, and could offer valuable insights into sustainable broodstock management.