Asian Journal of Fisheries and Aquatic Research
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Toxicological and Histopathological Effects of Psidium guajava Leaf Extract on African Catfish (Clarias gariepinus): Implications for Aquaculture
No full textPsidium guajava (guava) leaves are rich in bioactive compounds, including flavonoids, tannins, and saponins, known for their antimicrobial and antioxidant properties. These attributes have led to their incorporation in fish diets to enhance growth performance and health status. This study assessed the toxicological impact of ethanolic leaf extract of Psidium guajava on African catfish (Clarias gariepinus) fingerlings. Fish were exposed to varying concentration of the extract 0–10 mg/L for 96 h, with mortality, behavior, water quality, and histopathology evaluated. Results showed a concentration-dependent mortality (96-h LC₅₀ = 4 mg/L), significant declines in dissolved oxygen and pH, and abnormal behaviors including erratic swimming and respiratory distress. Gill lesions ranged from epithelial lifting to lamellar degeneration, while liver tissues exhibited steatosis, vacuolation, and necrosis at higher concentrations. The water temperature exhibited slight fluctuations throughout the 96-hour experimental period. The lowest temperature (26.1 °C) was recorded at the 8mg/l concentration of the extract after 96 hours, whereas the highest temperature (28.6 °C) was observed in the control group (0mg/l) after 24 hours. Statistical analysis revealed significant variations (p<0.05) at 48 and 72 hours, while no significant differences were observed at 24 and 96 hours across the various concentrations. These effects may relate to phytochemicals such as tannins, flavonoids, and saponins, which act as antioxidants at low levels but induce oxidative stress and cellular injury at higher doses. While P. guajava is valued for its antimicrobial and immunostimulatory properties, excessive concentrations impair organ function, reduce survival, and may compromise nutrient utilization and fillet quality, raising aquaculture and food safety concerns. Defining safe exposure thresholds and integrating biomarker assays in future work are essential to balance its potential benefits with toxicological risks
Reproductive Performance and Profitability of Local and Imported Clarias gariepinus Strains in Two Agro-ecological Zones of Cameroon
No full textBackground: Aquaculture production of most aquatic species currently farmed relies heavily on wild-type stocks with limited genetic improvement, resulting in low productivity. In recent years, intensive breeding of this species in urban and peri-urban areas has developed and the same strain of Clarias gariepinus broodstock is frequently reused for several generations for reproduction and exchanged among producers.
Aims: One of the constraints encountered by aquaculturist is the lack of control over the strains and their performances. This study was conducted to evaluate on-farm performance and profitability of imported and local strains of Clarias gariepinus cultivated in Cameroon.
Study Design: This study was carried out from February 01 to June 20, 2024 in the Western Highlands and the Monomodale Rainfall Forest Zone of Cameroon.
Methodology: Forty (40) farms rearing C. gariepinus were sampled and surveyed in the Western Highlands and the Monomodale Rainfall Forest Zone of Cameroon. The data was gathered via personal interviews. Descriptive analyses were used to characterize and evaluate the performance of Clarias gariepinus breeding in Cameroon. The socio-demographic characteristics of the farmers, the performance and the profitability of the farms according to the strains were compared using the Krustal-wallis and t-test respectively.
Results: At the end of this study, the results show that 57% of producers use local strains, 13% for imported strains and 30% do not control the origin of the strain used. The strains to be used are chosen either for their growth and immune resistance (producers of local strains) or for their growth only (producers of imported strains). The socio-demographic characteristics of producers did not significantly affect (p> 0.05) the choice of the strain. With the exception of the average daily gain, all the reproductive characteristics studied were significantly affected by the type of strain (p< 0.05). Thus, the imported strain has the highest significant values for hatching rates (76.66%) and survival at the third day, unlike the egg-laying rates (19.33%) and deformed larvae (2.66%) which were lower. As for the productivity and cost of the fry, the highest significant values (p< 0.05) were with the imported strain, i.e. 4.92 fry/gram of female and 26.03 CFA francs respectively.
Conclusion: In terms of productivity and profitability, the highest significant values were with the imported strain. However, the study shows that the local strain has the lowest production costs per fry, resulting in the highest profits per fry. However, the local stain shows greater variability in zootechnical and economic characteristics, which suggests it may respond more favorably to genetic selection
Cyanobacterial and Physicochemical Aspects of Water from Lake Bambili
No full textAims: The aim of the study was to determine the physicochemical qualities of water and toxic cyanobacteria from Bambili lake to assess its potability.
Study Design: Good water quality in the natural environment requires upstream management.
Place and Duration of Study: Study took place from June 2024 to May 2025 in the Bambili lake and in the laboratory of biology, Higher Teacher Training College of The University of Bamenda at Bambili.
Methodology: Cyanobacteria sampling was done using plankton net for phytoplankton, scraping rocks and pressing macrophytes for phytobenthos. Collected Samples were analyzed under a microscope. While, physicochemical parameters were sampled in situ and by laboratory testing on the water collected from the sampling sites for nitrates, total phosphorus, cadmium and lead by spectrophotometric methods.
Results: For the 3 sampling sites, the organic parameters were high in concentration with a value varying from 1.45 mg/l to 1.70 mg/l, and 0.25 mg/l to 0.32 respectively for nitrates and total phosphorus (standard: ≤0.1 mg/l and ≤0.05 mg/l respectively). This could be detrimental to the lake as it would promote eutrophication. The least available chemical was Cadmium ranging from 0.23mg/l to 0.34mg/l. The total richness of cyanobacteria was 167 species group in 80 genera, 38 families and 13 orders. The bulk of these cyanobacteria where found in the Oscillatoriales which are known to produce cyanotoxins like microcystins which are a class of hepatotoxins.
Conclusion: Bambili lake was polluted and toxic cyanobacteria were present and dense. Water from Bambili lake with a good upstream physicochemical treatment strategy would reduce cyanobacteria proliferation and eutrophication
Effect of the Type and Level of Yeast Incorporation in the Feed on Pellet Buoyancy, Survival and Growth Characteristics of Oreochromis niloticus
No full textThe effect of yeast type and incorporation level on pellet buoyancy and growth characteristics of Oreochromis niloticus was studied between February and May 2022 at the IRAD/fish farming station/Cameroon. For this, 420 fry were distributed in a comparable manner in 14 concrete tanks of 0.6m3. Seven experimental rations representing respectively the rations without yeast, at 1 ; 1.5 and 2% of incorporation rate of baking powder, then at 1 ; 1.5 and 2% incorporation rate of baker\u27s yeast were distributed randomly and in duplicate. The results show that the type and the incorporation rate of yeast affected significantly (P< 0.05) the floatability of the pellets. Feeds containing yeast, regardless of type or inclusion level, exhibited significantly longer floatation times than those without. Whatever the incorporation rate, the highest floatation times (5568 and 4029 seconds) were obtained in the diets containing 1% and 1.5% of baker\u27s yeast and baking powder respectively and the lowest (74 seconds) in the diet without yeast. The survival rate and growth characteristics studied were significantly (P< 0.05) influenced by the type and incorporation rate of yeast. The highest survival rate values (84% and 76%) were obtained with 2% and 1.5% of baking powder and baker\u27s yeast respectively, and the lowest values (70%) with 0% yeast. The highest significant values (P˂0.05) of live weight (17.33 and 17.27), weight gain (15.13 and 15.07) and average daily gain (0.252 and 0.251) were observed in the groups fed with rations containing 1.5 and 2% of baking powder and baker\u27s yeast respectively, while the lowest significant values were obtained in the groups receiving 0% and 1.5% of baker\u27s yeast. The use of 1% baker\u27s yeast or 2% baking powder is therefore recommended for the manufacture of pellets for Nile Tilapia to increase the buoyancy of the feed and improve growth performances.  
Reproductive Biology, Seasonal Variation of Flat-head Lobster Thenus orientalis (Lund, 1793) in Pethalai, Sri Lanka
No full textThe flat head lobster Thenus orientalis is an economically important species in the Indo-Pacific, supporting fisheries that yield more than 5,000 t annually in Southeast Asia. Despite its commercial value, detailed information on its reproductive biology—particularly the timing of spawning, size-related fecundity and regional reproductive variation—remains limited. This study examined the reproductive biology of T. orientalis in Pethalai, Sri Lanka, based on monthly samples collected from June 2021 to June 2024 (n = 407) from the commercial catch. Gonadosomatic index (GSI), size at sexual maturity, sex ratio, fecundity and ovarian development stages. Results indicate a bimodal spawning pattern, with the main reproductive peak occurring during September to March (north-east monsoon period) and a secondary peak around May to June. GSI values varied seasonally (~1–6 %), with maxima in April 2022 (4.35± 1.07 %), December 2023 (4.14±1.77 %) and January 2022 (4.04± 1.64 %). The size at maturity (carapace length) was estimated at 60.0 mm. The sex ratio approximated 1:1 overall (χ² = 0.011, p = 0.917), though temporal variation was significant (χ² = 270, p < 0.001). Fecundity ranged from ~50,000 to 75,000 eggs and showed a positive—but relatively weak—relationship with carapace length. Ovarian development comprised four stages (early maturing, late maturing, ripe and spawning); late maturing females dominated June–September, whereas spawning females predominated October–March. The carapace length–fecundity relationship differed across maturity stages, with stronger correlations at early development. These findings provide critical baseline data for management of T. orientalis fisheries in Sri Lanka. It can be recommended implementing seasonal closures during peak spawning periods and a minimum size limit of 60 mm carapace length to protect spawning females. Furthermore, the size–fecundity association and environmental influence on reproductive output underscore the importance of habitat conservation and ecosystem-based management in sustaining T. orientalis stocks
Assessment of Livelihood Status of Shrimp Farmers: A Comparative Analysis During and Post COVID-19 Pandemic
No full textThe study was conducted to assess the livelihood status of shrimp farmers during and after COVID-19 in tala upazila of Satkhira district from January to March 2024. Data were collected by using a well-structured questionnaire from 40 shrimp farmers. The study found that 32.5% of shrimp farmers were aged 31 to 40. Regarding education, 22.5% had only completed elementary school, while 37.5% had finished secondary school. The majority of shrimp farmers 62.5% were involved in agriculture. Presently, 60% of fish retailers were belong to small-sized families with 2 to 4 and 35% of 5to 6 members. However, in COVID-19, 62.5% shrimp farmer\u27s families belong to small-sized, respectively. before covid-19 majority had live in kacha house which comprised 32.5%, after covid-19 had significantly increased 35%, respectively. It was shown that fish retailers had a fairly good level of sanitary conditions after covid-19. at present time, 22.5% of shrimp farmers earn less than 20000 bdt, 35% of shrimp farmers earn 50,001 to 100000 bdt from the shrimp farm; during the pandemic 40% of shrimp farmers earned less than 20000 bdt, 30% and 22.5% of shrimp farmers earned 20,000 to 50,000 BDT and 50,001 to 100000 BDT respectively. During COVID-19, 22.5% of shrimp farmers were supported by the government. the enhancement of their livelihood condition will lead to an improvement in the fishing sector
Dietary Evaluation of Lactobacillus acidophilus Strain PR2 as a Probiotic on Growth, Immunity, and Water Quality in Major Carp (Catla catla)
No full textProbiotic candidates, Lactobacillus acidophilus, are recognised for their ability to produce extracellular enzymes (proteases, lipases, and amylases), form resilient spores, inhibit pathogens, and colonise the intestinal mucosa. The present study investigated the dietary effect of a probiotic strain, Lactobacillus acidophilus, isolated from the gut of healthy fish, on the growth performance, feed utilisation, survival, and immune response of major carp (Catla catla) fingerlings. Four experimental diets were prepared with probiotic supplementation at 0% (control), 0.5%, 1.0%, and 1.5% inclusion levels. The eight-week feeding trial was conducted in a Completely Randomised Design (CRD) with triplicate groups. Results showed significant improvements (p < 0.05) in final weight, specific growth rate, weight gain percentage, protease and lipase activity, and feed efficiency in fish fed with 1.5% probiotic supplementation compared to the control. Survival rate did not differ significantly among treatments. The findings indicate that dietary supplementation of Bacillus sp. strain PR2 enhances growth and digestive enzyme activity, improving nutrient assimilation and immune modulation in major carp fingerlings. This probiotic strain demonstrates potential for sustainable aquaculture applications. Therefore, Bacillus sp. strain PR2 represents an effective, natural, and eco-friendly probiotic candidate suitable for improving carp culture productivity while reducing reliance on antibiotics
Growth Performance and Cost-Effectiveness of Feeding Composite Nursing of Nile tilapia, Oreochromis niloticus and African Catfish, Clarias gariepinus Fingerlings with Two Feed Types and their Mixture
No full textThis study investigated growth performance and cost-effectiveness of 1:1 composite nursing of Nile tilapia, Oreochromis niloticus and African catfish, Clarias gariepinus fingerlings fed separately with the same brand of commercial feeds of tilapia, catfish and their equal mixture in hapa-in-pond system for 77 days. The study was conducted at the Aquaculture Research and Development Centre (ARDEC) of Water Research Institute (WRI) of the Council for Scientific and Industrial Research (CSIR), Akosombo, Eastern Region, Ghana. The studied treatments were A (tilapia feed use only), B (catfish feed use only) and C (equal mixture of tilapia and catfish feeds use). The two (2) feeds were declared to contain 40.0% crude protein (CP) each by the producer. The fingerling nursing was conducted in nine (9) fine mesh net hapas, each of dimensions 5.0 x 2.0 x 1.2 m; installed in about a 0.2-hectare earthen pond. The fingerlings of O. niloticus and C. gariepinus, at initial weight ranged between 1.2 and 1.5 g and mean weights 1.34 ± 0.08, 1.31 ± 0.10 and 1.32 ± 0.10 g for treatments A, B and C respectively, were stocked at 60 fingerlings hapa-1 at a ratio of 1:1. The fingerlings were fed manually at a declining rate of 10.0-4.0% of their biomass hapa-1, 3 times daily. The combined final mean weight ranged from 34.60 ± 1.95 to 38.52 ± 6.00 g. No significant differences (ANOVA, P > 0.05) were observed in growth performance indicators among all treatments. Computed profit indices ranged from 12.74 to 14.97 with that of A being the highest and B, the least. Findings of the study indicated that either tilapia or catfish feed of similar CP contents could be used for composite nursing of O. niloticus and C. gariepinus fingerlings. However, the cheaper one should be opted for; purely for reasons of cost-effectiveness
Dietary Red Amaranth Flour Enhances Growth of Sand Lobster (Panulirus homarus) Seedings
No full textSand lobster (Panulirus homarus) is an export commodity that increases annually. To increase production, lobster farming is carried out by maximizing feed combined with spinach to optimize feed absorption. The study aims to analyze the effect of spinach in moist feed on lobster growth and survival. The research was conducted from June to August 2025, located in Ekas Bay, Ekas Buana Village, Jerowaru District, East Lombok Regency, West Nusa Tenggara. The research method used a completely randomized design, with 5 treatments and 3 replicates. The treatments in the study were moist feed (A), moist feed + 4% red spinach flour (B), moist feed + 8% red spinach flour (C), moist feed + 10% red spinach flour (D), and moist feed + 12% red spinach flour (E). The lobsters were kept in 25-liter compartments suspended on a 2-meter-deep KJA frame at a density of 10 lobsters per compartment and were maintained for 54 days. The research parameters were absolute weight and length growth, SGR, and SR. The results showed that spinach flour supplementation had a significant effect on weight and length growth as well as SGR, but no significant effect on SR. The best growth was observed in the 4% spinach flour treatment (B), which produced weight and length growth of 1.50 g and 1.78 cm, SGR of 0.73%/h, and SR of 88.9%. Meanwhile, the absolute weight and length growth of the control treatment (A) was 0.98 g and 0.91 cm, with an SGR of 0.52%/h and an SR of 72.2%
Effect of Dietary Supplementation of Chlorella vulgaris on Liver Biomarkers and Lipid Profile on Clarias gariepinus
No full textClarias gariepinus is an important commercial fish species in Nigeria and is widely cultivated by many farmers. This study investigated the effects of dietary supplementation with Chlorella vulgaris on liver biomarkers and lipid profiles in Clarias gariepinus over 12 weeks. Five groups of fish were used in the study; one group served as the control, while the other four groups were fed different concentrations of the algae at 5%, 10%, 15%, and 20%. At the end of the feeding trial, the fish were anesthetized using clove oil, and blood samples were collected for analysis. The results indicated that the supplementation of C. vulgaris in the diets of C. gariepinus led to higher protein percentages (ranging from 43.0% to 47.3%) and lower levels of AST (230.0) and ALT (54.0) in the algae-fed groups compared to the control group, which had a protein percentage of 39.67, AST levels of 497.3, and ALT levels of 180.7. Additionally, the lipid profiles showed that the treated groups had better outcomes than the control group. The findings revealed significant variations in the fish\u27s serum biochemical parameters and lipid profiles across the different treatments. Therefore, this study highlights the positive impact of microalgae as a physiological booster in C. gariepinus