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This study was carried out to evaluate the growth performance and some haematological functions of. The fish of each stocking density were fed either a diet containing 40% Crude protein (CP) or 45% CP with a feeding rate of 3% body weight twice daily. The experiment was replicated thrice and it lasted for 12 weeks during which haematological parameters and plasma biochemistry were measured. From this study, haemoglobin (Hb) and Red Blood Cell (RBC) slightly increased in all treatments but the variation was not significant in relation to protein level in the diets. Plasma glucose increased significantly (P<0.05) in relation to the stocking densities. The plasma protein showed insignificant variation in relation to the stocking density but the variation was more pronounced (P<0.05) at the lowest stocking density as the protein level in the diets varied. It can be concluded that enhancing feed quality especially protein level in the fish diet may ensure faster growth, stress reduction and improve health status of the fish.

Effects of dietary Euphorbia heterophylla extract (EH) on growth performance, feed utilization and haemato-biochemical parameters in African catfish, Clarias gariepinus, juveniles were evaluated in this study. Diets fortified with EH at 0 (control), 0.5, 1.0, 1.5 or 2.0 g/kg were fed to the fish to apparent satiation for 84 days before challenging it with Aeromonas hydrophila. The weight gain, specific growth rate and protein efficiency ratio of fish fed EH-supplemented diets were significantly higher but lower feed conversion ratio (p < 0.05) than the control group. The villi height and width at the proximal, mid and the distal of the guts rose significantly with the increasing levels of EH from 0.5 to 1.5 g than the fish fed basal diet. Dietary EH enhanced (p < 0.05) the packed cell volume and haemoglobin, whereas 1.5 g EH boosted white blood cell, in relation to their counterpart in the control group. There were significant increase in the activities of glutathione-S-transferase, glutathione peroxidase and superoxide dismutase (p < 0.05) in the fish that were fed diets supplemented with EH than the control. Dietary EH also enhanced phagocytic activities, lysozyme activities and relative survival (RS) of C. gariepinus than the control group, with the highest RS obtained in fish that were fed diet containing EH at 1.5 g/kg level. These results revealed that the fish fed 1.5 g/kg dietary EH promoted growth performance, antioxidant and immune profiles, as well as protection against A. hydrophila infection.

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Morphometric and meristic data were used in this study to establish morphological variations within the largest genetically consistent groups of five wild populations of tilapia from Kyushu and Okinawa ecological regions of Japan. The genetic analysis based on mitochondrial DNA relatedness was used to determine the data range used for the morphological analyses. During the morphological analyses, the morphometric and meristic data were correlated by two multivariate statistical methods, such as PCA and LDA. Both statistical methods observed morphological differences of higher divergence in Okinawa contrary to Kyushu. Additionally, the statistical relationship between the estimated non-parametric test of ANOSIM (R = 0.21; p ˂ 0.05) and PERMANOVA (F = 4.20; p ˂ 0.05) indicated a higher magnitude of morphological separation, especially in Okinawa; nevertheless, water temperature, conductivity, and salinity levels vary widely in Kyushu than in Okinawa. All observed differences could be attributed to either genetic and/or environmental factors, which are major variables in influencing phenotypic variability. However, since tilapia in Japan experienced multiple introductions from different countries and environmental backgrounds, we recommend further studies under a controlled environment to ascertain the environmental responsiveness during morphological differentiation within a genetically consistent group of tilapia.

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Growth, mortality and exploitation rate of Selene dorsalis (Gill, 1863) from the continental shelf of Ghana (West Africa) were examined between July 2018 and June 2019. The study provided results on fishery dynamics parameters needed to estimate the stock status and characteristics of S. dorsalis in the coast of Ghana. Monthly length-frequency data were collected from 629 samples and analysed using fisheries models fitted in TropFishR package in R software. The von Bertalanffy growth parameters were utilised to analyse the population dynamics of the species using ELEFAN Simulating Annealing. Based on the estimates, the asymptotic total length (L∞) was 22.2 cm, the coefficient of growth (K) was 0.76 year-1, and the calculated growth performance index (phi) was 2.58 with Rn value of 0.55. The total mortality rate (Z) was 3.32 year-1 with a natural mortality rate (M) of 1.21 year-1 and fishing mortality rate (F) of 2.11 year-1. The exploitation rate (E) estimated for the species was above the optimum level of 0.5, which indicates that S. dorsalis is overexploited in the coast of Ghana. It can be concluded that the exploitation rate of S. dorsalis has exceeded the optimum limit, hence the need for enforcement and improvement of fisheries management measures such as mesh size regulations, capping of canoes, closed fishing seasons and compliance with fisheries policies.