World Aquacluture Magazine - September 2020

48 SEP TEMBER 2020 • WORLD AQUACULTURE • WWW.WA S.ORG poietic tissue in kidney and spleen and that the process of hemoglobin formation was slow but not distorted. There were also significant difference between post-infection catfish and those treated with neem extract at 7.5 mg/mL inWBC, HGB, RBC, HCT, MCV andMPV. These was also higher than posi- tive control catfish treated with aquaceryl antibiotic. The significant increase in values of those parameters could be attributed to the stress- mediated condition that prompts the release of new erythrocytes from the erythropoietic tissue to improve the oxygen carrying capacity of exposed fish blood with resultant higher values of erythrocyte count and hemoglobin concentration. The process of RBC formation was not distorted; however, the decrease in HCT, HGB, MCV, MCHC, MCH could be a result of hemolysis, hemodilution or anemia. FIGURE 1. A, abscess on body close to the pelvic fin seven days after inoculation with Staphylococcus aureus . B, haemorrhagic lesion on body of fish within seven days of inoculation with Staphylococcus aureus (Photos: F.A. Awe). FIGURE 2. Histological section of liver cells to different concentration of neem leaf extracts on S. aureus inoculated catfish. A, Normal liver from catfish used as control experiment. B, Diffuse vacuolar degeneration of the liver cells post-inoculation with S. aureus . C, Mild vacuolar degeneration of liver cells seven days after treatment with neem leaf extracts at 2.5 mg/ mL concentration against catfish inoculated with S. aureus . D, Normal to mild vacuolar degeneration of liver cells seven days after treatment with neem leaf extracts at 5.0 mg/mL concentration. E, Normal liver cells seven days after treatment with neem leaf extracts at 7.5 mg/mL concentration. F, Diffuse vacuolar degeneration of liver cells seven days after treatment with neem leaf extracts at 10 mg/mL concentration. G, Normal to mild vacuolar degeneration of liver cells seven days after treatment with aquaceryl antibiotic 10 mg/mL concentration against catfish inoculated with S. aureus ; Haematoxylin & Eosin, 400 × . FIGURE 3. Histological section of gills to different concentration of Neem leaf extracts on catfish inoculated with Staphylococcus aureus . A, Normal gills of catfish used as control experiment, P= Primary lamellae; S= Secondary lamellae; B, necrosis, atrophy and fusion of epithelial cells of secondary lamellae post inoculation with Staphylococcus aureus . C, Sloughing, necrosis and atrophy of epithelial cells of secondary lamellae seven days after treatment with neem leaf at 2.5 mg/mL concentration. D, normal gills seven days after treatment with neem leaf extracts at 5.0 mg/mL concentration. E, normal gills seven days after treatment with neem leaf extracts at 7.5 mg/mL concentration. F, normal to atrophy of epithelial cells of primary lamellae seven days after treatment with 10 mg/mL neem leaf extracts. G, normal to partial fusion of epithelial cells of secondary lamellae of the gills seven days after treatment with aquaceryl antibiotic at 10 mg/mL concentration on Clarias gariepinus inoculated with Staphylococcus aureus (H& E, 400 × ).