Journal of Aquatic Sciences

Assessing macrobenthic compositions and ecological status of Lagos Lagoon using AZTI marine biotic index

M. C. Aleobua,, J. A. Nkwoji, , M. N. Igwo-Ezikpe, , B.O. Bassey, — Tue, 24 Feb 2026 00:00:00 +0000

Coastal lagoons, such as the Lagos Lagoon, are ecologically significant ecosystems that are becoming increasingly vulnerable to human-induced stresses, such as urbanization, pollution, and industrial activity. This study evaluated macroinvertebrate compositions and ecological quality status of the Lagos Lagoon using the AZTI Marine Biotic Index (AMBI) to assess responses to these perturbations. Ten (10) stations were sampled across the Lagoon during both dry and wet seasons. Water and sediment samples were obtained using bottom water samplers and a Van Veen grab respectively, and analyzed for physicochemical parameters and macroinvertebrate compositions using standard techniques. Analysis of variance showed significant seasonal changes (p < 0.05) in water temperature, dissolved oxygen, salinity, conductivity, and total dissolved solids. Ten (10) taxa (abundance: 237 individuals) were recorded during the wet season and 9 taxa (abundance: 226 individuals) in the dry season. These taxa belonged to three phyla: Mollusca, Arthropoda, and Annelida. The Shannon-Wiener diversity index ranged from 0.77 to 1.91 (wet season) and 0 to 1.21 (dry season), suggesting low diversity. Simpson's dominance index ranged from 0.60 to 0.86 (wet season) and 0.08 to 0.74 (dry season). AMBI revealed a slight level of ecological disturbance across all Stations, except Stations 6 and 7, with moderate disturbance in both seasons. The findings improved the understanding of the impact of numerous stresses on benthic macroinvertebrate ecosystems and illustrated the usefulness of biotic indices in ecological assessments.

Icthyofauna composition and biodiversity of Okomu Wetland, Edo State, Southern Nigeria

S.I. Ehiorobo, , A.E. Ogbeibu, , C.U. Olowo, , G.N. Agali, — Tue, 24 Feb 2026 00:00:00 +0000

Fish and fishery products significantly contribute to global food security and nutritional needs. The present study was carried out to determine fish biodiversity of Okomu National Park, Niger Delta Region of Nigeria. The icthyofauna composition of the wetland was studied monthly from August to October, 2018 to compare the presence, distribution and abundance of fish species in the lotic (Okomu River and Arakhuan Stream) and lentic water bodies within the ecosystem. Fish samples were collected with fishing nets of various mesh sizes using the standard capture and return technique. The results of the study revealed 71 fish specimens belonging to six (6) Orders, eight (8) Families and twelve (12) species. The fish species recorded included: Xenomystus nigri, Petrocephalus bovei, Gnathonemus petersii, Pelmatochromis pulcher, Oreochromis aureus, Tilapia zilli, Tilapia dageti, Micralestes elongates, Citharinops distichodoides, Parachanna africana, Erpetoichthys calabaricus and Malapterurus electricus. No fish sample was observed in the temporary ponds under investigation. This may be due to predation, seasonality, and water quality. However, the lotic systems supported fish population, where 10 fish specimens were obtained from Arakhuan Stream while Okomu River had 61 specimens. The family, Cichlidae dominated in the study area and constituted Tilapia zilli (22.5%), Tilapia dageti (18.3%) and Oreochromis niloticus (16.9%) of the total catch. The study demonstrated that the lotic segment of the Okomu Wetland supported fish diversity and provided valuable baseline information for future research.

Influence of carrot, Daucus carota powder on growth performance and survival rates of Oreochromis niloticus fry

N.M. Chilaka, , A. Uka, — Tue, 24 Feb 2026 00:00:00 +0000

Improving the growth, resistance and survival of Nile tilapia (O. niloticus) in aquaculture has important role in optimizing the production and profits. Carrot (Daucus carota) is a potential local nutraceutical that has antioxidative and immunostimulant properties. This study was performed to investigate the influence of carrot powder added in fish feed on the growth, survival rate and food conversion ratio of O. niloticus. A 90-day experiment was conducted on Nile tilapia of an average body weight and standard length of 0.5±0.02g and 3.5 0±0.5 cm respectively. The experiment was conducted in 70 litre plastic bowls with a water volume of 40 litre and 20 fish per bowl were given five treatments in three replications. Different carrot powder proportions of 0%, 6.15%, 9.23%, 12.3% and 15.38% were administered. Growth performances and water quality variables were measured using standard procedure. The highest final weight of 5.04±0.05g was obtained at 15.38% inclusion of carrot powder. Similarly, the highest mean weight gain (MWG) of 4.56±0.12g was recorded at T5 (15.38% inclusion of carrot powder), while the least MWG (3.57±0.05g) was obtained at T1 (0% inclusion of carrot powder). Significantly higher (p<0.05) specific growth rate (2.33±0.03%/day), protein efficiency ratio (0.95±0.01) and the best food conversion ratio (3.00±0.03) were recorded in fish treated with 15.38% inclusion of carrot powder. Survival rate of 95.6±0.00% was recorded at 0% and 6.15% inclusion levels of carrot powder, while there was 100% survival at 9.23%, 12.3% and 15.38% carrot powder inclusion levels. The levels of water temperature, pH, dissolved oxygen and ammonia were maintained within the ranges of 25.32±0.58°C to 25.87±1.54°C, 6.34±0.71 to 6.54±0.76, 5.21±0.48mg/l to 5.88±0.65mg/l and 0.04mg/l respectively. The results showed that carrot powder had significant effect on mean weight gain, specific growth rate, food conversion ratio and protein efficiency ratio of O. niloticus

Influence of carrot, Daucus carota powder on growth performance and survival rates of Oreochromis niloticus fry

N.M. Chilaka, , A. Uka, — Tue, 24 Feb 2026 00:00:00 +0000

Assessment of terrestrial ecosystem services of Okomu National Park, Southern Nigeria

S.I. Ehiorobo, , A.E. Ogbeibu, — Tue, 24 Feb 2026 00:00:00 +0000

The destruction and unsustainable use of forest resources necessitated the establishments of protected areas (National Parks) in many countries including Nigeria. The study assessed the terrestrial ecosystem services of Okomu National Park between August, 2017 and January, 2019, with a view to assess its fauna and flora diversity. Three compartments (each approximately 1.5 km²) were selected for plant assessment, while eight compartments were used for animal assessment. The transect method was employed to evaluate species abundance by counting individuals within each transect. The survey recorded 16 terrestrial animal species, with Cercopithecus erythrogaster (White-throated monkey) being the most abundant (31.21%), while Naja sp., Xercus erythropus, Loxodonta africana cyclosis, Phataginus tricuspid and Synercus caffer nanus occurred the least (0.58 % each). For flora, 23 species were observed, with Ceiba pontandra (13.07 %), Ceitis bondii (11.59 %), Anthonatha macrophylla (10.14 %) and Rothmannia wipidia (11.59 %) as the most abundant plant species. The study revealed the wetland's diverse fauna and flora compositions, highlighting its importance for biodiversity conservation and ecosystem services. The park's potential for ecotourism, research, and recreation is substantial. It is also very important to involve surrounding communities in park management and resource use to help mitigate conflicts, illegal logging, and poaching. To ensure sustainable management, it is recommended that, more researches be carried out including ecosystem valuation.

Health risk assessment of heavy metals in Tympanotonum fuscatus along Mbo River, Cross River Estuary, South Eastern Nigeria

I.U. Wilson,, I.K. Esenowo,, M.U. Effiong, — Tue, 24 Feb 2026 00:00:00 +0000

Heavy metals are considered contaminants, and when present in aquatic environment, may lead to pollution of aquatic organisms through their toxic effects and bioaccumulation. Health risk associated with the consumption of contaminated sea food had become a global concern. The study was conducted to assess concentrations of heavy metals: lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu) and Iron (Fe) in Tympanotonum fuscatus samples, as well as estimating the potential human health risk associated with the consumption of this fish obtained from Mbo Channel of the Cross River Estuary. The USEPA Guidelines for health risk based concentrations were employed for estimation of target hazard quotient (THQ), hazard index (HI) and target cancer risk (TCR). Water quality variables were also measured following standard protocols. Results showed significant differences (p < 0.05) in metal contamination indices in both water and fish samples. The principal component analysis (PCA) results showed that the total variance was 92.48%, and PC 1 was represented by Cd and Cr while PC 2 was dominated by Pb. The results for HI were: Cr (2.541 mg/kg), Cd (7.131 mg/kg), Pb (1.657 mg/kg), Cu (0.344 mg/kg) and Fe (0.193 mg/kg). The levels of Pb, Cd and Cr in fish fresh all exceeded the WHO permissible limit of 1.0 mg/kg. Although these metals have not been associated to toxicity, a potential adverse health risk may be associated with the consumption of T. fuscatus from the estuary. TCR values of the metals analyzed showed that Cr and Cd had high potential cancer risk while Pb had moderate risk factor in humans over 70 years of consumption. The health risk associated with accumulated metals in T. fuscatus underscores the need for periodic biomonitoring of the Cross River Estuary system.

Growth performance of juvenile Clarias gariepinus fed dried Eichhornia crassipes leaf meal

O.A. Bubu-Davies, , A.I. Ilesanmi, , J.G. James, — Tue, 24 Feb 2026 00:00:00 +0000

The invasive water hyacinth (Eichhornia crassipes) poses a significant threat to aquatic ecosystems but also offers a potential alternative to expensive fishmeal in aquaculture feeds. The study evaluated the growth performance and survival of juvenile Clarias gariepinus (weight: 4.95±0.154 g and length: 9.07±0.378 cm) fed diets with varying levels of water hyacinth leaf meal (WHLM) as a fishmeal (FM) replacement. The diets were TD1 (100% FM), TD2 (25% WHLM), TD3 (50% WHLM), TD4 (75% WHLM), and TD5 (100% WHLM). A 49-day feeding trial, conducted in a controlled condition, monitored fish growth, survival and water quality parameters. The feeding experiment was conducted in fifteen plastic tanks of 50-liter capacity each stocked with 10 juvenile C. gariepinus. The fish were fed twice daily at 3% of body weight. The control diet (TD1 diet) exhibited the best growth, followed by TD2, TD3, TD4 and TD5 diets. Analysis of variance revealed significant differences (p < 0.05) in weight gain, specific growth rate, feed conversion ratio and average daily growth between the control and WHLM-containing diets. Water quality parameters remained within acceptable limits for juvenile C. gariepinus growth, indicating that WHLM can be a suitable partial replacement for fishmeal. The study therefore suggests 25% water hyacinth leaf meal as a promising diet for sustainable production of juvenile gariepinus.

Phytochemical composition of Syzygium aromaticum and its effects on growth performance and feed efficiency of Clarias gariepinus

A.E. Akpan, , M.U. Effiong, , I.K. Esenowo, — Tue, 24 Feb 2026 00:00:00 +0000

Nutraceuticals are natural substances that are food or part of food to provide medicinal and health benefits, and also have the potency to prevent and treat diseases. The present study evaluated phytochemical compositions of clove (Syzygium aromaticum) flower bud extract with a view to evaluating its potential as a natural dietary additive in Clarias gariepinus diet. Clove powder was incorporated at four levels (0, 5, 10 and 15%) of the experimental diets and fed to the fish in triplicate for 84 days. All analytical protocols followed standard procedure. Phytochemical screening of clove revealed the presence of primary metabolites: carbohydrates, proteins, and lipids (in trace to moderate amounts), as well as secondary metabolites: alkaloids, flavonoids, tannins, sterols, saponin, cardiac glycosides, and phenolic compounds. Proximate analysis of clove extract showed high levels of carbohydrates (46.65±0.006%) and lipids (21.67±0.003%), with a caloric value of 413.83 kcal/100g, while protein content was relatively low (8.05±0.006%). Mineral analysis revealed potassium (10.10±1.03 mg/100g) as the most abundant element, followed by calcium, phosphorus, iron, magnesium, and zinc. Nutrient analysis showed appreciable amounts of vitamins A, B1, B2, and C., while anti-nutritional factors such as oxalate and phytate were present in low concentrations. The catfish treated with 15% clove extract in diets had the best specific growth rate (0.46±0.67%/day), average daily growth (1.56±0.01g/day), food conversion ratio (0.131±0.00) and protein efficiency ratio (37.6±3.40). Fish condition factor and survival rates followed similar trend. The results suggested that S. aromaticum extract contained beneficial phytochemicals and essential nutrients which may be suitable for use as a natural feed supplement. These bioactive compounds enhanced fish growth and feed utilization which increased with inclusion levels in diets. Thus, the use of clove bud extract in catfish feed in hereby encouraged.

Effects of palm oil mill effluent sludge and sesame seed meal on growth and gut microbial communities of Clarias gariepinus juveniles

J.J. Bernard, , U.D. Enyidi, — Tue, 24 Feb 2026 00:00:00 +0000

High cost of fish feed and poor nutrition are the major setbacks in catfish culture. Fish oil enhances feed acceptance, organoleptic qualities and growth of fish. Thus, the combination of different lipids can increase growth and oxidative stability of fish.This study evaluated effects of palm oil meal effluent sludge and sesame seed meal on growth and gut microbiome of the African catfish, Clarias gariepinus. Five feeds were produced to vary in the inclusion levels of palm oil effluent sludge (POME) and sesame seed oil meal (SSM) in the following ratio: F1 (POME:SSM 400:0g), F2 (POME:SSM 300:100g), F3 (POME:SSM 200:200g), F4 (POME:SSM 100:300g) and F5 (POME:SSM 0:400g). Other ingredients were added at same levels while a sixth diet (commercial catfish feed) served as the control. African catfish of average initial weight of 10.7-14.2g were stocked at 15 fish per treatment with each treatment replicated three times and fed both the experimental and control diets for 90days. The fish were fed ad libitum. Determination of bacterial loads in fish parts were done using standard microbiological procedures while standard formulae were used to calculate various growth parameters. Results revealed that inclusion of POME and SSM in the diets of juvenile catfish had profound effects on the growth and food conversion ratio. Fish treated with F1 gave the best performance in terms of specific growth rate (SGR; 3.68±0.07%day-1 ) and food conversion ratio (FCR; 1.54±0.01). The gut morphology of the catfish showed that catfish fed F2 (300gPOME:100gSSM), had the highest gut weight (1.25±0.01g) and longest intestinal length (19.93±0.05mm) than catfish fed all other feeds (p<0.05).The catfish fed with F1 had dominant microbial communities of Gram -ve rod including Enterobacter sp. and Escherichia coli. Those fed F2 (POME:SSM 300g100g), had Gram +ve, non-spore forming anaerobic rod, Lactobacillus sp as dominant species while those feed F5 (POME:SSM0g:400g) had Gram-ve rod, Klebsiella sp as part of the dominant species. The outcome of the present study support the inclusion of more of palm oil mill wastes in fish feed formulation.

Influence of parental body weight on reproductive success and fry performance of hybrid catfish (Heterobranchus longifilis × Heterobranchus bidorsalis) in controlled hatchery conditions

J.C. Ikwuemesi,, E.I. Awom, , J.O. Nwagba,, O.C. Egesi, — Tue, 24 Feb 2026 00:00:00 +0000

Brood stock quality is essential to a successful and viable fish seed production. Determinant of this quality includes age, physical and genetic makeup. Influence of brood stock body weight on reproduction and performance of Heterobranchus longifilis × H. bidorsalis was studied. Brood stock pairs of varying weights (1 kg, 1.5 kg, and 2 kg) were artificially spawned, and resulting eggs incubated under controlled conditions. The experimental design involved six treatments, (Treatment 1=1kg, Treatment 2=1.5kg, Treatment 3 =2kg, all males = Heterobranchus longifilis while Treatment 4 =1kg, Treatment 5=1.5kg, Treatment 6 =2kg, all males = Heterobranchus bidorsalis), replicated thrice. Parameters assessed included egg count per gram, hatchability, weight gain, specific growth rate, feed conversion ratio (FCR), and survival rate over an 8-week period. Water quality parameters were maintained within optimal ranges. Treatments with moderate-weight females (T1, T2, and T4) produced higher egg counts per gram, while heavier females (T3, T5, and T6) yielded lower counts but with significantly higher hatchability rates. Eggs in T6 had the highest hatchability (56.33%). Growth performance indicators: final weight (5.37±0.47 to 5.07±0.52g), FCR (2.81±0.26 to 3.23±0.50), SGR (0.6697±0.0710 to 0.6608±0.1031%/day) and survival rate (58.33 ± 2.52 to 52.00±10.44%) did not differ significantly (p > 0.05) among treatments, indicating uniform post-hatching performances. The findings highlight a trade-off between fecundity and egg viability, larger brood stock may enhance hatchability despite reduced egg output. For optimal hatchery productivity, brood stock selection should consider not just egg quantity but also fertilization success and larval viability.

Design strategies of cast nets in Escravos Estuary within Okerenkoko axis of Delta State, Nigeria

T.E. Binyotubo, , O.I. Binyotubo, , K. Kwen, — Tue, 24 Feb 2026 00:00:00 +0000

Fishing gear design is the process of preparing technical specifications that will aid in providing sections of the gear drawing. This painstaking examination is to ensure proper gear handling technique and operation, including satisfying economic and social considerations. The design strategies of cast net in Escravos Estuary within Okerenkoko, Delta State, Nigeria was studied in three stations: Station 1 {University Jetty (UJ)}, Station 2 {Zion Jetty (ZJ)} and Station 3 {Vigilante Jetty (VJ)} between April and June, 2025. Two types of castnets were identified in the study area. The cast nets had length circumference ranging from 4.0 to 8.0 m, the retrieval lines measuring between 3.0 to 6.0 m while the thickness ranged from 3.0 to 6.0 mm. The netting material used in the study area consisted of R 100 – 310 tex polyamide twines of z – twist disposition with stretched mesh sizes ranging from 25 to 50 mm with hanging ratio of 0.5. It was observed that the netting section of the cast nets were horizontally segmented into panels.The segmented cast nets consisted of two to three segments and each segment was found to be made of netting with different mesh sizes (50 mm, 30 mm and 25 mm) and R – tex twine sizes. This range of mesh sizes observed in most of the cast nets in the study area were in line with the Inland Fisheries Decree 108 of 1992, especially cast nets used in fishing species such as Ethmalosa fimbriata and Sardine llaaurita in the study area. The results revealed that, polyamide nettings were the most commonly used materials in constructing the cast nets, and this polyamide netting materials are highly recommended for use in constructing cast nets due to their high quality and tensile strength. This is a pilot study in the area for cast nets fisheries, but more studies are still needed to provide tangible recommendations.

Efficacy of metomidate as anaesthetics in clarias gariepinus (Burchell, 1822) broodstock and its effects on water quality

O.A. Bubu-Davies, , O.O. Orokotan, — Tue, 24 Feb 2026 00:00:00 +0000

Anaesthetics are commonly used in aquaculture to minimize the incidence of stress in fish. The study assessed effects of metomidate as anaesthetics on induction and recovery time in male and female brood fish of Clarias gariepinus as well as on some water quality variables {pH, dissolved oxygen (DO), temperature, ammonia and nitrite}, following standard procedures. Thirty-six (36) brood C. gariepinus consisting of eighteen (18) gravid female (mean length 60.23 cm±0.36 and 2.64 kg ±19.36) and eighteen (18) matured male (mean length 58.12 cm ±0.47 and 1.98 kg ±45.11 were exposed to 0.00 (control), 2.00, 4.00, 6.00, 8.00 and 10.00 mg/L in triplicates. Results showed that induction time(s) in both sizes of exposed fish decreased (660.00±18.98 at 2.00 mg/L to 228.00±20.72 at 10.00 mg/L) as metomidate concentration increased, while the recovery time(s) increased as metomidate concentration increased (490.00±23.07 at 2.00 mg/L to 862.00±28.15 at 10.00 mg/L). The survival rates in male and female C. gariepinus exposed to metomidate were 100.00 % (0.00 mg/L and 6.00 mg/L of metomidate). The results indicated that metomidate did not cause any significant change (p>0.05) in water quality variables in all exposure concentrations. A reduction in DO, (5.22±0.78 mg/L in the control to 4.96±1.16 at 10 mg/L anaesthetics concentration) and slight increase and decrease in ammonia (0.35±0.01 mg/L; 0.28±0.11 mg/L) and nitrite (0.02±0.01 mg/L; 0.03±0.01 mg/L) were observed at 6.00 to 10.00 mg/L of metomidate. The study therefore established 4.00 mg/L as ideal concentration for C. gariepinus exposure to metomidate for optimum production in aquaculture venture.

Growth performance evaluation of Clarias gariepinus, Heterobranchus bidorsalis and heteroclarias under recirculatory and flowthrough aquaculture systems

I. Abdulraheem, , N.A. Bamidele, , S.I. Adegbesan, , H.A. Ayodeji, — Tue, 24 Feb 2026 00:00:00 +0000

Aquaculture system design plays a critical role in influencing the growth performance and survival of cultured fish species, particularly in intensively farmed catfish. This study evaluated variations in growth performances and survival rates among two widely cultured catfish species in Nigeria (Clarias gariepinus and Heterobranchus bidorsalis) and their hybrid (Heteroclarias) under flow-through and recirculatory aquaculture systems. Three Hundred (300) hatchery bred fry (14 day old) each of C. gariepinus, H. bidorsalis and Heteroclarias were randomly selected and stocked separately in triplicate (100 fish/replicate) experimental plastic tanks (1.2 x 0.6 x 0.5m3 ) connected to recirculatory and flow-through systems. The fish were fed ad libitum four times daily with commercial feed (40% CP) for 60 days. Growth performances and survival rates of the fish were estimated according to standard formulae. Data collected at the end of the feeding trials were subjected to t-test and one way analysis of variance. Results showed that final mean weight and weight gain (WG) differed significantly (p < 0.05) among treatments. Fish reared in recirculatory system generally recorded higher final weights and weight gains when compared with those reared in flow-through system. C. gariepinus in the recirculatory system achieved the highest final weight (4.34 ± 0.13 g) and weight gain (4.25 ± 0.12 g), while the lowest values were observed in C. gariepinus and H. bidorsalis reared under flow-through conditions. Daily growth rate values ranged from 0.06 to 0.07 g day⁻¹, while specific growth rates ranged from 6.21 to 6.68%day⁻¹. The highest survival rate was observed in Heteroclarias reared in the recirculatory system (88.78 ± 1.09%) and lowest in H. bidorsalis under flow-through conditions (86.22 ± 0.62%). In conclusion, recirculatory systems enhanced catfish growth and survival, with the hybrid strain (Heteroclarias) showing superior growth performances when compared with the parent stock (C. gariepinus and H. bidorsalis) in both culture systems.