Asian Journal of Fisheries and Aquatic Research

Assessment of the Genotoxic Potential of Mancozeb and Propiconazole Fungicides in the Freshwater Catfish Clarias batrachus: A Study Protocol

2026-07-11T13:19:44+00:00

Background: Mancozeb and propiconazole are widely used agricultural fungicides that can enter freshwater bodies through surface runoff and may affect non-target aquatic organisms. Clarias batrachus, a freshwater catfish of ecological and food-fish significance, is frequently associated with habitats exposed to agricultural effluents and provides a suitable model for cytogenetic assessment because of its nucleated erythrocytes. This study protocol outlines an approach for assessing the genotoxic potential of mancozeb and propiconazole, individually and in combination, in C. batrachus. The proposed design includes acute and chronic exposure scenarios, sub-lethal concentrations derived from LC₅₀ values, and biomarker-based evaluation of DNA damage in blood, gill, liver and kidney tissues. The principal endpoints include the alkaline comet assay, micronucleus test and chromosomal aberration analysis, supported by oxidative stress markers such as SOD, CAT, GPx and MDA. Molecular analysis of DNA repair and stress-response genes is also proposed to clarify possible mechanisms of toxicity. The protocol further emphasises environmentally relevant exposure conditions, mixture-toxicity assessment and standardised sampling procedures. The expected outcome is a structured framework for generating species-specific evidence on fungicide-induced genotoxicity in C. batrachus. Such data may support aquatic biomonitoring, ecological risk assessment and future management of pesticide contamination in freshwater environments.

Observations on the Types of Deformed Larvae Encountered during Induced Spawning of a Threatened Catfish, Ompok bimaculatus (Bloch,1794)

2026-07-10T10:37:04+00:00

Larval deformity is a recurring hatchery concern because it reduces seed quality, production efficiency, growth and survival. The present study recorded and categorised the visible morphological anomalies encountered during induced spawning and hatching of the threatened butter catfish, Ompok bimaculatus. Broodfish weighing 90–120 g were collected during July, and females were induced with Ovatide at 1 mL/kg body weight. Eggs obtained after stripping were fertilised with sperm suspension prepared from harvested testes and incubated in a flow-through plastic-tub hatchery. Approximately 300–400 fertilised eggs were placed in each hatching tub, and hatching was allowed for 24–26 h. Deformed larvae were collected from four breeding attempts, segregated initially using a magnifying glass and confirmed under a stereozoom microscope. The observed deformities were classified as teratoma, acephala, dwarf larvae and axial deformity. Teratoma was characterised by an undifferentiated embryonic mass without distinct body parts; acephala showed an indistinct head region; dwarf larvae were smaller than normal hatchlings; and axial deformity involved bending or multiple curvatures of the trunk and/or tail. Normal larvae were 4–5 mm long, whereas some deformed larvae were 2–3 mm or 2.6–3.1 mm long. Deformity was generally 5–7% during usual breeding operations and increased to 10–15% during late breeding. The observations indicate that visible larval deformities are important practical indicators of hatchery seed quality in O. bimaculatus.

Impact of Helminth Infection on Physiological, Hematological, Biochemical, and Immune Parameters of Ornamental Fishes from Latur District, Maharashtra, India

2026-07-11T07:04:31+00:00

Helminth infections are among the major health challenges affecting ornamental fish culture, leading to physiological stress, metabolic disturbances, and impaired immune function. This study evaluated the association between naturally occurring helminth infections and physiological, haematological, biochemical, immunological, and parasitological parameters in ornamental fishes collected from aquarium fish shops and culture units in Latur District, Maharashtra, India. A total of 120 ornamental fishes representing ten commercially important species were examined and categorised into healthy (n = 45) and helminth-infected (n = 75) groups following parasitological screening. Comparative analyses were performed using an independent Student's t-test at a significance level of p < 0.05. Helminth-infected fishes exhibited significantly lower body weight, condition factor, hepatosomatic index, gonadosomatic index, haemoglobin concentration, erythrocyte count, serum protein, cholesterol, triglycerides, lysozyme activity, and total immunoglobulin levels than healthy fishes. Conversely, leukocyte count, serum glucose concentration, liver enzyme activities (AST, ALT, and ALP), and respiratory burst activity were significantly higher in infected fishes, indicating physiological stress and altered innate immune responses. The overall prevalence of helminth infection was 62.5%, with the highest prevalence observed in koi carp and Oscar fish. These findings demonstrate a significant association between helminth infection and deterioration of physiological condition, haematological profile, metabolic status, and immune function in ornamental fishes. The study highlights the importance of routine health monitoring, effective parasite management, and improved biosecurity practices for sustainable ornamental aquaculture.

Feeding Habits, Length-weight Relationship and Condition Factor of Spotted Tilapia (Tilapia mariae; Boulenger, 1899) (Pisces: Cichlidae) in the Adofi River, Niger Delta, Nigeria

2026-07-13T07:46:56+00:00

The food and feeding habits of fish have long attracted considerable attention from researchers, as they constitute a fundamental basis for the development and implementation of effective fisheries management programmes in both capture and culture fisheries. A comprehensive understanding of feeding ecology provides valuable insights into trophic interactions, resource utilisation, growth performance and habitat requirements, thereby facilitating the sustainable exploitation, conservation and management of fish populations. Cichlids are a dominant fish family in the Adofi River, and Tilapia mariae forms a significant component of local diets. The present study aimed to provide information on the food, feeding habits and growth characteristics of T. mariae from a stretch of the Adofi River, Niger Delta, Nigeria. The natural food of the species was studied from the stomach contents of 250 fish samples measuring 5.1-17.5 cm standard length and weighing 18.7-229.4 g. Stomach contents were analysed using the frequency of occurrence, numerical, fullness and point methods. Green algae, diatoms and desmids were the main food items of plant origin. Filamentous algae were the most preferred food items of plant origin, occurring in more than 90.0% of the fish examined. Coleoptera, diptera, trichoptera and chironomid larvae were the food items of animal origin. Feeding intensity varied seasonally, with peaks during the wet season. Tilapia mariae in the Adofi River was a daytime feeder, as the number of stomachs containing food items was significantly higher (P < 0.05) during the day (176) than at night (11). The fish showed a negative allometric growth pattern (b < 3). Monthly condition factor ranged from 2.0 to 3.2 and varied with individual fish length. Condition factor was higher during the wet season months. The baseline ecological data obtained for the first time on this species in the river, a first-order tropical stream in the Niger Delta, will provide information for future fish growth and food analyses, as well as for fisheries exploitation, management and conservation.

Growth Performance and Survival of Nile Tilapia (Oreochromis niloticus) Fed Raw Black Soldier Fly Larvae Meal in an Aquaponic System

2026-07-14T04:42:09+00:00

Background: The high cost of aquafeeds limits the profitability of tilapia farming, particularly in low-input production systems. Black soldier fly larvae meal (Hermetia illucens) appears to be a local and sustainable protein source that can be used in aquaponic systems.

Aims: This study evaluated the effects of raw black soldier fly larvae meal on the growth performance and survival of Nile tilapia (Oreochromis niloticus) juveniles reared in an aquaponic system in Côte d’Ivoire.

Study Design: A comparative experimental design involving two dietary treatments was used.

Place and Duration of Study: The experiment was conducted in Côte d’Ivoire over a 52-day experimental period.

Methodology: A total of 428 fry, with an initial mean weight of 1.3 g, were distributed into four rearing tanks and fed either raw black soldier fly larvae meal (BSFL) or a commercial control diet. Water quality parameters, the biochemical composition of BSFL meal, growth performance, survival rate, feed conversion ratio and protein efficiency ratio were evaluated.

Results: Water quality parameters remained within acceptable ranges for tilapia culture, with no significant difference between treatments (p > 0.05). BSFL meal contained 39.11% crude protein, 9.40% lipid, 10% ash and 9.86% moisture. Fish fed the commercial diet showed significantly better final mean weight, weight gain, daily weight gain, feed conversion ratio and protein efficiency ratio than those fed BSFL meal (p < 0.05). However, survival rates remained high and comparable, reaching 90.67 ± 0.70% in the BSFL group and 89.16 ± 1.54% in the control group.

Conclusion: Despite lower growth performance, raw BSFL meal appears to be a local and sustainable alternative protein source for low-input aquaculture systems. Its nutritional optimisation could improve fish growth and strengthen its use in sustainable aquaponic production systems.

Proximate Composition of Fresh and Smoked-dried Gymnarchus niloticus from Markets Along the Orashi River, Rivers State, Nigeria

2026-07-18T07:49:34+00:00

This study evaluated the proximate composition of fresh and smoked-dried Gymnarchus niloticus obtained from three markets along the Orashi River axis of Rivers State, Nigeria: Mbiama, Ndoni, and Omoku. Eighteen samples were collected monthly for three months, comprising three fresh and three smoked-dried samples from each location, and were analysed using standard proximate analytical procedures. The data were subjected to one-way analysis of variance, and mean separation was performed using Duncan's multiple range post-hoc test at P < .05. The results showed that smoke-drying significantly influenced the proximate composition of the fish samples. Moisture content was higher in fresh samples, ranging from 65.89% in Mbiama to 70.53% in Omoku, but declined markedly in smoked-dried samples, with values ranging from 13.99% in Ndoni to 18.26% in Mbiama. Crude protein increased after smoke-drying, from 14.98-18.83% in fresh samples to 65.08-72.40% in smoked-dried samples, indicating concentration associated with moisture reduction. Ash content also increased from 1.89-2.40% in fresh fish to 5.43-6.86% in smoked-dried fish, suggesting a relative increase in mineral concentration. Crude fat and carbohydrate contents generally decreased after drying, although the extent of change varied among the markets. Crude fibre showed smaller changes, with values differing across sample form and location. Significant differences were observed among samples from different locations and between processing forms, indicating that both market origin and smoke-drying contributed to variation in proximate composition. The findings provide baseline compositional information on G. niloticus from the Orashi River markets and show that smoke-drying substantially changes its moisture, protein, ash, fat, fibre, and carbohydrate profiles.

Seasonal Dynamics and Host-specific Infection Patterns of Intestinal Cestodes in Economically Important Freshwater Fishes of Chorakhali Dam, Dharashiv (Formerly Osmanabad), Maharashtra, India

2026-07-18T09:43:59+00:00

Aims: This study investigated the seasonal dynamics and host-associated infection patterns of intestinal cestode parasites infecting economically important freshwater fishes from Chorakhali Dam, Maharashtra, India. The objectives were to determine the prevalence, mean intensity, and seasonal variation of cestode infections and to evaluate host–parasite associations under natural environmental conditions.

Study Design: A field-based observational parasitological study.

Place and Duration of Study: Chorakhali Dam, Dharashiv (formerly Osmanabad) District, Maharashtra, India, from June 2022 to April 2026.

Methodology: A total of 237 freshwater fishes representing commercially important species were collected from different sampling sites and examined for intestinal cestode infections using standard parasitological techniques. Recovered parasites were fixed, stained, mounted, and identified using established taxonomic keys. Parasitological indices, including prevalence, mean intensity, mean abundance, and host-associated occurrence, were calculated. Seasonal differences in infection were analysed using the Chi-square test and one-way ANOVA, with statistical significance accepted at P < 0.05.

Results: Among the 237 fishes examined, 108 (45.57%) were infected with intestinal cestodes. Infection prevalence differed significantly among seasons (P < 0.05), with the highest prevalence recorded during summer (60.26%), followed by winter (44.30%), and the lowest during the monsoon season (32.50%), consistent with the seasonal distribution presented in Table 3. Mastacembelus armatus exhibited the highest infection prevalence and was predominantly infected with Senga spp., whereas Circumoncobothrium spp. occurred mainly in Channa species. Mean parasite intensity and abundance were also significantly higher during summer (ANOVA: F = 14.27, P = 0.001), suggesting favourable environmental conditions for parasite transmission.

Conclusion: The present study demonstrates that intestinal cestode infections in freshwater fishes from Chorakhali Dam exhibit pronounced seasonal variation and distinct host-associated occurrence. Summer represents the peak transmission period, whereas monsoon conditions are associated with reduced infection. These findings provide baseline information for fish health surveillance, parasite management, and sustainable inland fisheries in Maharashtra.

Abundance and Diversity of Gastropoda Associated with the Mangrove Ecosystem in Jor Bay, West Nusa Tenggara Province, Indonesia

2026-07-18T09:52:08+00:00

Mangrove ecosystems support diverse benthic communities, including gastropods that contribute to litter breakdown and may reflect habitat condition. This study assessed the genus-level composition and community structure of gastropods in the mangrove ecosystem of Jor Bay, East Lombok Regency, West Nusa Tenggara Province, Indonesia. Field sampling was conducted in April 2026 using a stratified random design across ten stations. At each station, gastropods were collected from three 1 × 1 m subquadrats established within a 10 × 10 m quadrat. Specimens were identified to genus level, and abundance, Shannon–Wiener diversity, Pielou’s evenness, and Simpson’s dominance indices were calculated. In total, 606 individuals representing nine genera were recorded at eight stations. The genera identified were Nerita sp., Terebralia sp., Littorina sp., Nassarius sp., Turricula sp., Clypeomorus sp., Chicoreus sp., Cerithidea sp., and Telescopium sp. Terebralia sp. was the most abundant and dominant genus, whereas Telescopium sp. was the least abundant. Diversity values ranged from 0.7436 to 1.3418, indicating low to moderate diversity. Evenness values ranged from 0.4620 to 0.9023, representing moderate to high evenness, while dominance values ranged from 0.3956 to 0.6575. Muddy substrates predominated at the stations where gastropods occurred and were associated with the widespread occurrence of Terebralia sp. These findings provide baseline information on the spatial variation and community structure of mangrove-associated gastropods in Jor Bay.

Invasion of Nile Tilapia (Oreochromis niloticus Linnaeus 1758) and its Effects on Indian Major Carp Production in Singotam Reservoir, Telangana, India

2026-07-18T12:03:55+00:00

Telangana is predominantly an inland fisheries state, with abundant lakes, reservoirs, dams, rivers, backwaters, and irrigation tanks. Indian major carps (IMCs) are widely consumed and cultured because of their texture and characteristic taste and their contribution to rural fisher livelihoods. In recent years, invasive fishes have entered open water bodies and adversely affected fisheries-dependent communities. This study was conducted from January 2023 to December 2025 to assess the association between Nile tilapia (Oreochromis niloticus) invasion and IMC catch composition in Singotam Reservoir, Nagarkurnool District, Telangana, India. Monthly fish-landing data were collected at the landing centre, and catches were graded by species and size with the assistance of local fishers. Nile tilapia accounted for approximately 76% of the cumulative catch, whereas IMCs accounted for 24%. The annual contribution of Nile tilapia increased from 63.26% in 2023 to 82.81% in 2025, while the IMC contribution declined from 36.74% to 17.19%. Catch composition differed significantly between fish categories and sampling years (p < 0.001). The decline in the IMC contribution despite periodic seed stocking suggests possible interspecific competition, although the landing-based design does not establish causality. The findings indicate a shift in reservoir catch composition towards Nile tilapia dominance and support the need for integrated catch monitoring, scientifically planned IMC stocking, targeted tilapia removal, and habitat-based management to sustain IMC productivity.

Sexual Segregation of Blacktip Reef Sharks (Carcharhinus melanopterus) at Mitita Island, South Morotai, North Maluku, Indonesia

2026-07-20T12:23:37+00:00

Sexual segregation may influence habitat use, social interactions, and population organisation in reef-associated sharks. However, habitat-based and social segregation in blacktip reef sharks (Carcharhinus melanopterus) at Mitita Island remains insufficiently understood. This study investigated habitat-based and social patterns of sexual segregation in blacktip reef sharks (Carcharhinus melanopterus) at Mitita Island, South Morotai, North Maluku. Field observations were conducted at Mitita Point and Niomi Point over eight sampling days from June to August 2024, comprising 24 dives. Individual sharks were recognised through photo-identification using natural markings on the dorsal and caudal fins. Environmental conditions, benthic cover, reef fish abundance, shark occurrence, and agonistic interactions were recorded. Eighteen individuals were identified, including 12 females and 6 males. Females occurred more frequently at Mitita Point, which had greater live coral cover, higher reef fish abundance, and calmer current conditions, whereas males were observed more frequently at Niomi Point. Exploratory Poisson regression indicated that current velocity score and salinity were associated with female occurrence; none of the measured environmental variables significantly predicted male occurrence. Analysis of “Give Way” interactions suggested that females occupied more central positions within the observed interaction network. The findings indicate sex-related differences in spatial occurrence and social interactions within the local aggregation. However, these patterns should be interpreted cautiously because the study involved a small identified population, two sampling stations, a short observation period, an observational design, and controlled feeding during diver-based surveys. Longer-term, seasonal, non-provisioned monitoring and movement-tracking approaches are required to determine whether the observed patterns persist across time and habitats.