Asian Journal of Fisheries and Aquatic Research

Spice Combination and Its Comparative Effect on Proximate Composition and Microbial Load of Smoked Clarias gariepinus

P. C. Onuoha — Fri, 07 Aug 2026 00:00:00 +0000

Fish, a major source of animal protein in Nigeria, is lost annually to spoilage because of improper storage and inadequate preservation techniques. Synthetic antioxidants have gradually lost their use and value in the industry because of their reported undesirable effects. Furthermore, synthetic preservatives are not readily available and are expensive for local fish processors. Hence, there is a need for natural and locally sourced preservatives. This study investigated the effects of spice combinations on the microbial load and proximate composition of smoked Clarias gariepinus. Four treatments were used, each with three replicates. Treatment 1 comprised Monodora myristica, Zingiber officinale and Piper guineusis. Treatment 2 comprised Monodora myristica, Zingiber officinale and Xylopia aethipica. Treatment 3 comprised Monodora myristica, Zingiber officinale and Allium sativum, whereas treatment 4 comprised a brine solution and served as the control. The smoked fish was stored for 21 days and sampled every 7 days. The total coliform count (TCC) results showed higher initial values for all treatments, with no significant differences (p > 0.05) among them. After smoking, the TCC values decreased in all treatments, with treatment 4 recording the highest value (1740), which differed significantly (p < 0.05) from those of the other treatments, followed by treatment 1 (1300). The total viable count (TVC) results showed that the initial values were higher than those obtained after treatment and during storage. After smoking and after 1 week of storage, treatment 4 recorded the highest TVC values of 2640 and 2240, respectively, which differed significantly (p < 0.05) from those of the other treatments. Treatment 2 recorded the lowest TVC values of 940 and 1120, respectively, which were also reported as significantly different (p > 0.05) from those of the other treatments. The proximate composition results showed that the moisture content of treatment 2 after smoking differed significantly (p < 0.05) from those of the other treatments, whereas treatments 1, 3 and 4 did not differ significantly (p > 0.05). Crude protein content generally did not differ significantly (p > 0.05) among treatments at the initial assessment, after smoking or at the end of storage. The findings indicated that smoked fish treated with M. myristica, Z. officinale and X. aethipica (treatment 2) had the best performance.

Abundance of Sailfin Armoured Catfishes Pterygoplichthys sp. (Loricariidae), African Catfish Clarias gariepinus (Clariidae) and Tilapia Oreochromis sp. (Cichlidae) in Open Waterbodies of Mahabubnagar District, Telangana State, India

Laxmappa Boini, Ravinder Rao Bakshi — Fri, 07 Aug 2026 00:00:00 +0000

Non-native fish species, particularly Pterygoplichthys sp., Clarias gariepinus, and Oreochromis sp., have been introduced into many regions outside their native ranges for various purposes. The rapid spread and establishment of invasive populations, recently reported in certain open waterbodies of Mahabubnagar district, Telangana, are of increasing concern because of their adverse effects on commercial fisheries. To assess the current invasion status and impact dynamics of these exotic species in four selected open waterbodies (Tankara- Peddacheruvu tank, Buddaram- Gudemcheruvu tank, Ibrahimbad- Hemasamudram tank, and Tirmalagiri- Shankarasamudram tank) a 12-month field survey was conducted from April 2025 to March 2026. Fish-catch data for sailfin armoured catfish, African catfish, tilapia, and other commercially cultured major carps were obtained during harvesting from the selected waterbodies. Catch composition at the landing centres was analysed, and the harvested fish were graded by species and size. The results showed high relative abundance (RA) values for sailfin armoured catfish (24.92%), tilapia (10.72%), and African catfish (4.71%), whose established populations affected cultured carp species during the study period. These findings provide evidence of the successful invasion of sailfin armoured catfish, tilapia, and African catfish. The study highlights the need for appropriate measures to support effective planning for native commercial carp production. The data generated indicate that exotic species pose a serious threat to native fish biota and cause substantial economic losses to fishing communities.

Reproductive Traits in Catfish Sperata seenghala Sykes, 1839 in Gomati River of Tripura, North East India

Sukanta Banik, Dipak Das — Fri, 07 Aug 2026 00:00:00 +0000

Reproductive information is essential for understanding fish population dynamics and supporting appropriate management measures. This study characterised the sex ratio, gonadal maturity stages, length at first maturity, gonadosomatic index, spawning seasonality, and fecundity of Sperata seenghala in the Gomati River, Tripura, North East India. Specimens were collected from five riverine locations between January and December 2022 using traditional cast nets and drag nets. Sex was determined through external examination and, when required, macroscopic examination of the gonads. Maturity stages were classified using a five-stage scale, while reproductive indices and fecundity were estimated using established procedures. Among 357 fish assessed for sex ratio, females constituted 67.5% and males 32.5%. Mature and ripe individuals occurred mainly from May to September, and the gonadosomatic index reached its highest value in July in both sexes. The length groups at first maturity were 35.0–39.9 cm for males and 40.0–44.9 cm for females. Absolute fecundity, estimated from 50 ripe females, ranged from 20,123 to 47,376 eggs and showed positive relationships with total length, body weight, and ovary weight. The maturity pattern and oocyte-size observations indicated that the species is a single spawner with a prolonged breeding season associated with the monsoon. These findings provide location-specific baseline information on the reproductive biology of S. seenghala that may inform conservation planning, harvest regulation, and future captive-breeding work in Tripura.

Dietary Supplementation of Moringa Leaf Powder: Effects on Growth Performance, Survival and Stress Indicators in Rainbow Trout, Nepal

Mahendra Prasad Bhandari, Binita Acharya, Sushma Sharma — Tue, 11 Aug 2026 00:00:00 +0000

Rainbow trout culture can be constrained by stress and disease, creating interest in plant-based feed additives. This study evaluated the effects of dietary Moringa oleifera leaf powder (MLP) at 0, 20, 30 and 40 g/kg feed on growth performance, survival, hepatosomatic index (HSI) and plasma cortisol in rainbow trout under Nepalese raceway conditions. Three hundred fish with an average initial weight of 55.31±0.46 g/fish were allocated equally to four treatments, each with three replicates, and fed at 3% of body weight twice daily for 90 days. Water quality was monitored, growth and feed-utilisation indices were calculated, HSI was determined and plasma cortisol was analysed using an enzyme-linked immunosorbent assay. MLP40 produced the highest final weight (110.83±1.82 g), specific growth rate (0.76±0.02%/day) and daily weight gain (0.61±0.02 g/fish/day), together with the lowest feed conversion ratio (2.13±0.02). Survival did not differ significantly among treatments. The HSI and water-quality parameters also showed no significant treatment effects. Plasma cortisol declined with increasing MLP supplementation and was lowest in MLP40 (13.89±3.86 ng/mL), compared with 44.01±1.97 ng/mL in the control. Under the conditions of this study, supplementation at 40 g/kg feed was associated with improved growth performance and feed utilisation and a lower plasma cortisol concentration, without significant changes in survival or HSI. Moringa oleifera leaf powder therefore shows potential as a functional feed additive for rainbow trout culture.

Properties of Chitosan Extracted from Waste Scales of Labeo rohita of Lucknow, U.P., India

Shyam Dev Maurya, Amrit Pritam Rout — Tue, 11 Aug 2026 00:00:00 +0000

Fish processing in tropical countries generates substantial quantities of waste, including scales, heads, and fins, which may be discarded into soil and water. This study investigated the recovery of chitosan from waste scales of Labeo rohita collected in Lucknow, Uttar Pradesh, India. The scales were washed, sun-dried, and subjected to sequential demineralization, deproteinization, and deacetylation. The recovered chitosan was evaluated for yield, degree of deacetylation, moisture content, ash content, and solubility. Structural, morphological, and thermal characteristics were examined using Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The extraction process produced a chitosan yield of 27%. The degree of deacetylation was 62.71%, while the moisture and ash contents were 3.16% and 0.962%, respectively. The material was soluble in a 1% aqueous acetic acid solution. The infrared spectrum contained bands associated with hydroxyl, carbon-hydrogen, amide, carbon-nitrogen, and carbon-oxygen groups. Scanning electron micrographs showed irregular, non-homogeneous, agglomerated particles with a rough surface and visible pores. Thermogravimetric analysis indicated an initial loss associated with adsorbed moisture, followed by degradation of the polymeric structure. These findings document the recovery and physicochemical characterization of chitosan from discarded L. rohita scales under the extraction conditions used in this study.

Diversity and Distribution of Marine Gastropods in the Subtidal Zone of Hutumuri Waters, Ambon, Indonesia

Wed, 12 Aug 2026 00:00:00 +0000

Marine gastropods are important components of tropical benthic ecosystems, and their assemblages can provide information on habitat conditions. This study assessed the species composition, ecological density, abundance, frequency of occurrence, community structure, and bathymetric distribution of marine gastropods in the shallow subtidal zone of Hutumuri Village, Ambon Island, Indonesia. Sampling was conducted from February to April 2026 along six transects established perpendicular to the shoreline and separated by 100 m. Gastropods were recorded in 5 × 5 m quadrats positioned at 25 m intervals across depths of 2, 4, 6, 8, and 10 m. A total of 28 species belonging to 24 genera, 14 families, and three orders were identified, with Neogastropoda representing the most species-rich order. Coralliophila violacea had the highest ecological density (5.67 individuals m⁻²) and abundance (approximately 72,000 individuals ha⁻¹), while Conus figulinus had the highest frequency of occurrence (approximately 90%). Community indices indicated moderate species diversity (H′ = 2.87), high evenness (J′ = 0.86), and low dominance (D = 0.08). Species richness declined from 22 species at 2 m to 13 species at 10 m. These findings show that gastropod composition and distribution varied along the sampled depth gradient, with shallower habitats supporting greater species richness. The study provides baseline information for monitoring gastropod assemblages and supporting the management of shallow subtidal habitats in Hutumuri waters.

Risk Management Strategy for Nile Tilapia (Oreochromis niloticus) Farming Business: A Case Study in Bojongsoang District, Bandung Regency, Indonesia

Wed, 19 Aug 2026 00:00:00 +0000

Aims: This study aimed to identify risk events and risk agents affecting Nile tilapia (Oreochromis niloticus) farming and to formulate priority mitigation strategies for farmers in Bojongsoang District, Bandung Regency, Indonesia.

Study Design: A descriptive qualitative survey with a case study approach was conducted, and risks were analysed using the House of Risk (HOR) method.

Place and Duration of Study: The study was undertaken in Nile tilapia farming ponds in Bojongsoang District, West Java, Indonesia. Data were collected in August 2025, followed by processing and analysis through July 2026.

Methodology: Forty-six respondents were selected through purposive sampling according to predefined research criteria and field conditions. HOR stage 1 was used to identify risk events and agents and calculate Aggregate Risk Potential (ARP), followed by Pareto analysis to determine priority risk agents. HOR stage 2 was then used to rank preventive actions according to the Effectiveness to Difficulty (ETD) ratio.

Results: Eleven risk events and 24 risk agents were identified. Fourteen priority risk agents accounted for 81.78% of total ARP, with pond water quality factors predominating. The three highest-priority mitigation actions were improving pond control management, stabilising pond water-source quality, and enhancing pond aeration.

Conclusion: The findings indicate that water quality management is central to risk control in the study area. Phased implementation of the prioritised mitigation actions may support the productivity and sustainability of Nile tilapia farming.

Production Performance and Feed-related Economics of Pangasius Cage Culture in the Sriram Sagar Reservoir, Telangana, India: A field-scale Case Study

Sat, 22 Aug 2026 00:00:00 +0000

Reservoir cage aquaculture can generate substantial fish biomass without constructing additional ponds, but production and financial performance depend on stocking, survival, feed conversion, water exchange and market price. We documented a field-scale Pangasius cage-culture unit in the Sriram Sagar Project at Pochampad, Telangana, India. The production unit comprised ten rectangular floating cages, each measuring 6 m × 4 m × 4 m (96 m³), with a combined culture volume of 960 m³. A total of 26,000 approximately 3-inch-long fingerlings were stocked at 27.1 fish m⁻³ and cultured for 7–8 months using CP Company floating feed containing 22% crude protein. Survival was 85%, corresponding to an estimated harvest population of 22,100 fish. Total marketable production was approximately 20,000 kg, equivalent to 2,000 kg cage⁻¹, a harvest biomass density of 20.8 kg m⁻³ and a calculated mean harvest weight of 0.905 kg per surviving fish. At an apparent feed conversion ratio of 1.50, estimated feed use was 30,000 kg and feed expense was INR 11.55 lakh at INR 38.50 kg⁻¹. A farm selling price of INR 120 kg⁻¹ generated gross sales of INR 24.00 lakh and a feed-adjusted return of INR 12.45 lakh before other production costs. Routine monitoring classified the major freshwater physicochemical parameters as being within acceptable operating ranges. The case demonstrates the production and income potential of conservative reservoir cage stocking while emphasising the need for continued numerical environmental monitoring, complete feed and mortality records, and full enterprise costing.

Assessment of Ichthyofaunal Diversity of Kanjia Lake, Odisha, India

Sanjaya Kumar Parida, Pranati Patnaik — Mon, 24 Aug 2026 00:00:00 +0000

Kanjia is a freshwater lake in Odisha situated between Nandankanan Zoological Park and the Botanical Garden and spreads over an area of 105 hectares. The lake is important for supplying water to the zoo, providing a source of livelihood for local fishermen, and supporting visitor recreation. It has great vertebrate diversity, particularly fish fauna. This study was undertaken from January 2022 to December 2024 in Kanjia Lake of Nandankanan Zoological Park over a period of 3 years to obtain baseline information on its fish diversity. During the study, fish samples were collected and identified, and their scientific names, local names, conservation status and taxonomic classification were recorded following standard literature. We collected and identified a total of 31 fish species belonging to 7 orders and 14 families and found that the order Cypriniformes showed maximum diversity, with 11 species, while the family Cyprinidae was the most dominant, with 10 species. We found that 29 species were Least Concerned (LC), while two were Near Threatened (NT). Regarding seasonal availability, some fish were available in all three seasons, whereas maximum diversity was observed in the post-monsoon season. Fish diversity in the lake is affected by various anthropogenic factors, macrophyte infestation, declining water levels and the invasion of predatory species.

Small-Scale Breeding and Early Fry Culture of Betta splendens Using Artemia Nauplii: A Case Study from Government Arts & Science College (A), Kamareddy, Telangana, India

M. Sathvika, K. Pavan Kumar, P. Padmavathi, Malsoor Thirumala — Tue, 25 Aug 2026 00:00:00 +0000

Betta splendens, commonly known as the Siamese fighting fish, is a commercially important ornamental freshwater species valued for its colour diversity, fin morphology and distinctive bubble-nesting behaviour. This study documented small-scale breeding and early fry culture of B. splendens using Artemia under controlled aquarium conditions at Government Arts & Science College (A), Kamareddy, Telangana, India, from February to April 2026. One well-developed male and one well-developed female were maintained separately and conditioned for 10 days with high-quality Artemia feed. Breeding was conducted in a glass aquarium measuring 46 × 22 × 22 cm, with a calculated gross capacity of 22.26 L. Water temperature was maintained at 27–28°C, pH at 7.2–7.5, dissolved oxygen at 4–6 mg L⁻¹ and ammonia at 0 mg L⁻¹. The system contained freshwater, smooth pebbles, aquatic plants, an Indian almond leaf, clean floating bubble wrap, gentle aeration and filtration, and a secure top cover. The male was placed in the breeding aquarium for 24 h to establish territory and construct a bubble nest. The female was then held in a transparent container within the same aquarium for 12 h to permit visual acclimation without physical contact, after which she was released during the morning under close observation. Spawning produced an estimated 150–180 eggs. The female was removed immediately after spawning to prevent post-spawning aggression, while the male remained for egg and larval care and was removed after the fry became free-swimming. Freshly hatched Artemia nauplii were supplied during early fry culture. By the end of the three-month observation period, approximately 45–48 juveniles remained alive and growing, corresponding to an apparent egg-to-juvenile retention of 25.0–32.0%. The study demonstrates the feasibility of low-cost Betta breeding and Artemia-supported fry culture at the degree-college level, while highlighting the need for replicated trials and systematic measurement of fertilisation, hatchability, water quality, feed intake and growth.

Occurrence of Invasive Sailfin Armoured Catfishes Pterygoplichthys spp. (Loricariidae) in Palkonda Wetland, Mahabubnagar District, Telangana, India

Laxmappa Boini, Ravinder Rao Bakshi — Thu, 27 Aug 2026 00:00:00 +0000

The Palkonda- Peddacheruvu tank (16°44'34.7"N & 78°01'53.9"E) in the outskirts of Mahabubnagar town in Telangana, India is a sewage-fed, nutrient-rich waterbody used for fish production for the livelihood of local fishers. The sailfin armoured catfish (Pterygoplichthys spp.), exotic to India, has invaded this wetland. The management and control of this catfish have been hindered because of the lack of information on its abundance, population structure, biological traits, level of establishment, and competition with native fish species. The survey conducted in July 2026 indicated the occurrence of these exotic Pterygoplichthys spp. and their initial impacts in the wetland through the collection of samples, catch data, and fishers experiences. Amazon sailfin catfish Pterygoplichthys pardalis and vermiculated sailfin catfish Pterygoplichthys disjunctivus and inter-grades (hybrids) of these two species have invaded this waterbody. The length (TL) and weight of the specimens ranged from 36 to 51 cm and from 347 to 1103 g, respectively. The results recorded in the study confirm the dominance of this genus in the surveyed area, with a relative abundance of 50.48% compared with tilapia (37.91%) and commercial carps (11.61%). Pterygoplichthys spp. have successfully colonised the sensitive Palkonda- Peddacheruvu tank and might easily spread to neighbouring water bodies and cause ecological and economic disturbance unless preventive measures are taken, as the genus poses a high invasive risk in the region.

Comparison of Maceration and Ultrasonic Extraction Methods for Visual Saponin Screening in the Macroalga Sargassum polycystum

Zara Oktari Surur Asmi, Edwin Jefri, Lulu Adilla Latifah — Thu, 27 Aug 2026 00:00:00 +0000

Sargassum polycystum is a brown macroalga containing various bioactive compounds, including saponin, which has considerable potential for pharmaceutical and nutraceutical applications. This study aimed to compare the effectiveness of conventional maceration and ultrasound-assisted extraction (UAE) methods for the qualitative screening of saponin from S. polycystum. Samples were collected from Teluk Kodek, North Lombok, Indonesia, freeze-dried, powdered, and extracted using 70% ethanol, 96% ethanol, and 96% methanol at a sample-to-solvent ratio of 1:20 (w/v). Conventional maceration was performed for 24 h using an orbital shaker (150 rpm), whereas UAE was conducted for 30 min at 50º C. The obtained extracts were concentrated using a rotary evaporator and subjected to qualitative phytochemical analysis using the foam test to determine the presence of saponins. The result demonstrated that both extraction method and solvent type significantly influenced saponin detection. In the conventional maceration method, the extract obtained with 70% ethanol and 96% methanol tested positive for saponins. In comparison, the 96% ethanol produced the highest and most stable foam formation, indicating a greater abundance of saponins. In contrast, extracts indicate that ultrasound-assisted extraction using 70% ethanol is the most effective approach for the qualitative extraction and screening of saponins from S. polycystum. The study highlights the importance of selecting appropriate extraction techniques and solvents to maximize the recovery of bioactive compounds from brown macroalgae.

Effects of Year, Species and Rearing Environment on Synthetic and Androgen Efficacy for Sex Reversal in Nile and Blue Tilapia

Sat, 29 Aug 2026 00:00:00 +0000

Monosex, all-male tilapia culture can improve production efficiency by preventing uncontrolled reproduction and associated growth losses. This study evaluated the effects of masculinising treatment, species, rearing environment, and production year on sex-reversal success in Nile tilapia (Oreochromis niloticus) and blue tilapia (Oreochromis aureus). A retrospective four-year dataset (2020–2023) comprised 1,200 fries distributed across two species, two rearing environments, and three treatments: 17α-methyltestosterone (MT), honey, and goat testis extract (GTE). Reversal proportions were assessed using descriptive statistics, Pearson chi-square tests, pairwise two-proportion z-tests, and multivariable binomial logistic regression. MT produced the highest reversal rate (80.0%), compared with honey (64.0%) and GTE (58.0%), and the treatment effect was significant (χ² = 47.04, p < .001). The controlled pond culture environment produced a higher reversal rate than the open field pond (74.0% versus 60.7%; χ² = 23.65, p < .001). The difference between O. aureus and O. niloticus was marginal (70.0% versus 64.7%; p = .056), while outcomes were identical across the four production years. Logistic regression identified MT (OR = 2.97) and controlled rearing (OR = 1.90) as significant independent predictors. A significant treatment × environment interaction indicated that the advantage of MT was greatest under controlled conditions. Honey and GTE achieved lower but measurable masculinisation, warranting further assessment under standardised conditions.

Advances in Mud Crab Scylla spp. Fattening: A Critical Synthesis of Production Systems, Nutrition, Water Quality, Health Management and Emerging Technologies

John Yesudhas — Mon, 31 Aug 2026 00:00:00 +0000

Mud crab fattening is a short-cycle aquaculture strategy in which lean, recently moulted, low-condition or otherwise under-finished market-sized crabs are held until flesh condition, gonadal development or market grade improves. Its apparent simplicity conceals a tightly coupled production problem: feeding intensity influences water quality; confinement changes aggression and disease transmission; salinity and oxygen modify metabolism and immune competence; and the biological meaning of weight gain depends on moult stage, sex, species and the endpoint chosen. This critical narrative review evaluates advances in fattening of mud crabs of the genus Scylla, with emphasis on production systems, nutrition, water-quality control, health management and emerging technologies. Literature was selected through international and regional scholarly sources for the period 1 January 1998 to 23 June 2026, with earlier evidence retained when conceptually necessary. The strongest direct evidence supports individual compartmentalisation where cannibalism or contact-mediated disease threatens survival, and indicates that controlled recirculating systems can improve environmental stability when salinity, solids and nitrogenous waste are actively managed. Nutritional evidence is less transferable than commonly assumed: protein and amino-acid requirements derived from postlarvae or juveniles cannot be treated as universal targets for short-cycle finishing of market-sized crabs, while direct fattening studies favour stage-specific formulated diets that balance nutrient density with low waste generation. Water-quality studies demonstrate important effects of salinity, temperature, hypoxia and ammonia, but many are acute or juvenile experiments and therefore define biological hazards more reliably than farm operating thresholds. White spot syndrome virus, mud crab reovirus, Hematodinium and pathogenic Vibrio spp. remain important health risks, with evidence increasingly linking disease control to isolation, stress reduction and environmental management rather than treatment alone. Emerging recirculating, habitat-enriched, precision-feeding and digital monitoring approaches are promising, but commercial validation, energy accounting and smallholder affordability remain insufficiently resolved. The field would benefit most from species-verified, stage-specific, farm-scale trials that integrate biological performance, product quality, disease outcomes, resource use and economics.