Asian Journal of Fisheries and Aquatic Research

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

2026-08-07T07:44:01+00:00

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

2026-08-07T12:20:32+00:00

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

2026-08-07T12:27:08+00:00

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

2026-08-11T09:11:18+00:00

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

2026-08-11T09:16:50+00:00

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

2026-08-12T10:58:09+00:00

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

2026-08-19T12:50:57+00:00

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

2026-08-22T09:56:17+00:00

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.