Journal of Fisheries

Effects of dietary supplementation of peppermint (Mentha piperita) on growth, survival and haemato-biochemical profile of common carp (Cyprinus carpio) fingerlings

Basant Singh — 2026-03-14

Herbal feed additives are increasingly explored in aquaculture as natural alternatives to synthetic growth promoters and immunostimulants. Peppermint (Mentha piperita), known for its bioactive phytochemicals and antioxidant properties, has shown potential benefits for fish health and metabolism. A 60-day feeding trial was conducted using 120 fingerlings (initial mean weight: 10.2±0.02 g; length: 9.63±0.03 cm) randomly distributed into four experimental groups, each with three replicates, following a completely randomized design. Experimental diets were prepared by incorporating peppermint leaf powder at 0% (control), 1%, 2%, and 3% per kg of feed weight (designated as T1, T2, and T3, respectively). After 60 days, fish fed the diet containing 3% peppermint (T3) exhibited significantly higher (p < 0.05) weight gain, protein efficiency ratio, average daily growth, and specific growth rate compared to other treatments. A significant increase (p < 0.05) in white blood cell (WBC) count was also recorded in the T3 group, indicating enhanced immune response. No significant differences were observed in red blood cell count, haemoglobin, packed cell volume, platelets, lymphocytes, monocytes, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, or mean corpuscular volume among treatments. No mortality was observed in any group throughout the experimental period. Overall, dietary supplementation with 3% peppermint leaf powder improved growth performance, stimulated immune function, and maintained normal hematobiochemical parameters in common carp, supporting its potential as a safe and effective natural additive in sustainable aquaculture.

How to protect water sources from microplastic contamination?

Muhammed Atamanalp — 2026-03-10

Microplastics (MPs) have emerged as one of the most widespread and persistent pollutants of the 21st century, posing profound challenges to aquatic ecosystems, biodiversity and human health. Derived from both primary and secondary origins, MPs are leaching into aquatic systems through synthetic textiles, vehicle components, personal care products and domestic wastewater discharge. Once in aquatic environments, they exhibit high chemical stability and adsorptive capacity, acting as vectors for persistent organic pollutants (POPs), heavy metals and pathogenic microorganisms. The resulting bioaccumulation and biomagnification across trophic levels causes cellular oxidative stress, immunotoxicity, endocrine disruption and reproductive impairment in aquatic organisms, thus extending ecological risk to humans through trophic transfer. This compilation of recent studies concludes that the MP crisis is not only an environmental problem but also a systemic reflection of unsustainable production and consumption patterns. Addressing this challenge requires global cooperation, integrating scientific expertise with socio-political action and redefining economic growth within the limits of planetary health. This review examines the multidimensional nature of MP pollution, its sources, pathways and impacts on environmental integrity, while proposing strategic frameworks for the protection of global water resources.

Spatial variation in the otolith shape of Asian sheat catfish, Wallago attu (Bloch & Schneider, 1801) populations from five Indian rivers

Graish Kumar — 2026-03-09

The population of Wallago attu (Bloch & Schneider, 1801) has declined worldwide including in the rivers of India and has been declared ‘Vulnerable’ by the International Union for Conservation of Nature. The restoration and conservation of fishes is heavily dependent on their population status in their natural habitats. Therefore, otolith shape was used to study the stock structure of W. attu from rivers Ganga, Gomti and Yamuna in Northern India, river Hooghly in Eastern and Pampa in Southern part of India. Shape indices of the asteriscus otoliths and elliptical Fourier analysis of the contour shapes was investigated using univariate and multivariate statistical techniques. The otolith descriptors (otolith length, breadth, area and perimeter) and four shape indices (length-breath ratio, form factor, circularity and ellipticity) of the otoliths were different (ANOVA, p<0.05) between the fish of five sampled rivers. Principal component analysis of normalized elliptical Fourier descriptors (NEFDs) of the contour shape accounted for 89.55% of the total variance. Discriminant function analysis on the basis of NEFDs resulted in 100% classification rate with no intermixing between the fish of different rivers and depicted the presence of different stocks of W. attu in a scatter plot of DF-I against DF-II. These variations in the otolith shape in the current study might be due to the restricted movement of fish because of geographical isolation and different environmental conditions in different rivers due to changes in habitat, or both. The current study would be helpful in developing effective strategies for stock management of this species.

Pathogenicity and molecular characterization of cyprinid herpesvirus-2 (CyHV-2) infecting Hypophthalmichthys molitrix in India

Supratim Malla — 2026-03-09

Cyprinid herpesvirus-2 (CyHV-2), a linear double-stranded DNA virus of the genus Cyprinivirus (family Alloherpesviridae), is a significant pathogenic agent responsible for herpesviral hematopoietic necrosis disease (HVHND), causing severe mortality in cyprinid fishes. While CyHV-2 is well documented in goldfish and crucian carp, information on its pathogenicity in Chinese carps remains limited. The present study investigated a severe disease outbreak in carp polyculture systems, with a focus on Hypophthalmichthys molitrix, integrating epidemiological observations, pathology, molecular characterization, and experimental infection trials. Affected fish exhibited clinical signs, including lethargy, hemorrhages, and respiratory distress, accompanied by extensive gross and histopathological lesions involving the gills, kidney, spleen, and musculature. CyHV-2 was detected by PCR in both diseased and apparently healthy fish, suggesting subclinical infection or transient viral presence. Sequence analysis of the partial DNA polymerase gene showed 94.95% identity with the virulent Asian strain CNDF-TB2015 and clustered within the CyHV-2 clade, confirming the virus identity. Experimental infection using tissue-derived inocula showed differential pathogenicity, with kidney (upto 80%) and gill-derived inocula (70%) inducing significantly higher mortality (log-rank test, p < 0.005) than liver-derived inocula (10%). Bacteriological analysis revealed concomitant Aeromonas infection, suggesting viral-bacterial synergism during disease outbreaks. Collectively, the findings implicate CyHV-2 as a primary viral agent involved in the outbreak and highlight kidney and gill tissues as critical targets for pathogenesis. This study provides the first integrated pathological, molecular, and experimental evidence of CyHV-2 pathogenicity in carp polyculture systems and underscores the need for routine surveillance to mitigate emerging viral threats in aquaculture.

Microplastic pollution in edible marine fish from the northwestern Bay of Bengal, Bangladesh: A comprehensive assessment of occurrence, characteristics and associated ecological risks

Maria Zaman — 2026-03-04

Microplastic (MP) pollution is an emerging environmental issue with serious implications for marine ecosystems and potential risks to human health. This study assessed MP contamination in the gastrointestinal tracts of 130 individuals representing 13 species (n=10 species^–1) from the Bay of Bengal, Bangladesh. A total of 892 MP particles were detected, confirming ubiquitous contamination across all species. MP abundance ranged from 3.70–12.00 items per individual (mean±SD: 6.87±1.08 items fish^–1). Five morphotypes: fibers, films, foams, pellets, and fragments were identified, with fibers constituting the dominant category. Most MPs were <5 mm, and red was the most common color. MP abundance exhibited a moderate positive correlation with body length (r=0.41), indicating that larger individuals tended to contain higher numbers of MP. Benthopelagic species exhibited the highest MP ingestion (7.85±2.58 items fish^–1), while carnivorous fishes showed greater contamination (7.13±2.59 items fish^–1) among trophic guilds. Risk assessment revealed that contamination factor (CF) ranged from 1.00–3.24, indicating moderate to high levels of MP contamination. The overall polymer load index (PLI) was 1.76, corresponding to a low pollution risk category. However, polymer hazard index (PHI) analysis revealed dominance of moderate-risk polymers, including polyester and PP–PE copolymer, with high-risk polymers such as nylon (PHI = 8.80) and PVC (PHI = 7.00) contributing substantially to overall hazard. These findings provide baseline evidence of MP contamination in Bangladeshi marine fisheries and highlight the need for future studies integrating polymer toxicity, trophic transfer, and human exposure pathways to support effective mitigation strategies.