Assessment was carried on the growth and microbial flora presence in African catfish (Clarias gariepinus) larvae fed with live food(Artemia) and commercial feed (Aller Aqua). Two days old larvae (n=200) of average weight (4.8± 0.01mg)and length (6.16±0.03mm)were reared in triplicates for 21 days in plastic tanks (40cm x 25cm x 25cm) dimension. The experiment was done in 12 hours static and 12 hours flow through periods each day. The physico-chemical parameters were within acceptable range for catfish culture except in the static periods were ammonia was present in values (0.30 ± 0.00) that are unacceptable. However, nitrate and nitrite were present but in low values. Both feeds showed commendable performance in growth parameters, but Artemia with lower crude protein content did better. There were presence of Total heterotrophic bacteria, Vibro, Total coliform and Salmonella/Shigella in the microbial analysis of the fish waters in all the treatment. Apart from total heterotrophic bacteria that was significantly present in all the experimental waters Vibro, Total coliform and Salmonila/Shigella were less than thirty(<30)cfu. Also, fish gets olderthe quantity of microbial flora present in the fish waters reduces.

The experiment was carried out to evaluate the prophylactic efficiency of dietary powdered Persea americana leaves on the organosomatic indices, disease resistance, and liver histopathology of Clarias gariepinus exposed to Klebsiella pneumoniae. Five (5) different isonitrogenous diets with varying percentages of P. americana powered leaves inclusion were formulated as follows: Do(0%); D1(3%); D3 (6%); D3 (9%) and D4 (12%). One hundred and fifty (150) C. gariepinus were distributed in five groups in triplicates of ten (10), and fed diets Do-D4 accordingly. After eight (8) weeks of feeding, they were injected intraperitoneally with klebsiella pneumoniae at days 1, 7, 14 and 21. After twenty eight (28) days post-infection period, three fish from each of the triplicate were sacrificed for evaluation of the Hepatosomatic index (HSI); Cistosomatic index (CSI), and Spleenosomatic index (SSI), and the liver was taken to the laboratory for histopathological analysis. The survival rate was calculated in each of the groups and the disease resistance was determined. At the end of the experiment, serious ulcerations were observed on the fish fed Do and infected with K. pneumonia, while the fish fed D1 – D4 were ulcer- free. The result reveals that the SSI and CSI were similar in all the groups (Do-D4), but the HSI was higher (P>0.05) in the group fed Do (control) compared to the group fed D1-D4. The survival rate and the diseases were Lower (<0.5) in the group Do compared to the group fed D1-D4, though it was not dose dependant. The result of the histopathology shows that the liver of the fish fed Do has bloodstain in the portal vein and sinusoid, while the liver of the fish fed D1-D4 have no bloodstain. The experiment reveals that Persea americana powdered leaves as applied is an anti-liver inflammatory herb, disease resistant and anti-bacterial.

The phytochemcial content of P. americana powdered leaves was assessed using ethanol extracts. The potency of the powdered leaves was assessed by exposing C. gariepinus fed different levels of the dietary powdered leaves (Do: 0% leaves inclusion; D1: 3% leaves inclusion; D2: 6% leaves inclusion; D3: 9% leaves inclusion and D4: 12% leaves inclusion diets) for eight weeks to K. pneumonia via intrapretoneal injection. The fish were injected after the 8 weeks feeding at day 1, 7, 14 and 21. The haematological parameters and microbial load (antibacterial activities) of the infected fish organs were assessed 28 days after the first injection. The ethanol extracts of the P. americana leaves powder revealed the following phytochemicals: phenol, carotenoids, alkaloids, flavonoids, saponin, steroids, coumarine and proanthocyanidin in varying quantities. The haematological parameters in the infected fish compared to the control Do indicated that there were improved Pack cell volume (PCV), Haemoglobin (Hb) and Red blood cells (RBC) in fish fed D2-D4 compared to the fish fed Do (control). The white blood cells (WBC), the lymphocytes, Monocytes and Eosinophils were higher (P>0.05) in the fish fed Do compared to the fish fed D1-D4. The Red blood indices (MCH, MCHC and MCV) fluctuated in values across the diets, but were higher in fish fed D1. The microbial load was higher (P<0.05) in the organs (Kidney, spleen, liver and blood) of the fish fed Do compared to the rest, and the effect was dose dependent. The results showed that P. americana powdered leaves improved the haematological and antibacterial activities of the experimental fish.

Clarias gariepinus were infected with Aeromonas hydrophila and Pseudomonas aeruginosa, and blood samples were collected weekly for biochemical analysis to analyse their enzyme activities and pathogenesis for four weeks. The enzymes includes: aspartate aminotransferase (AST), alkaline phosphastase (ALP), acid phosphastase (ACP) and lactate – dehydrogenase (LDH). The fish were distributed in three different groups in triplicates as: control (C1 C2 C3), A. hydrophila (A1, A2, A3) and P. aeruginosa (P1, P2, P3). After two weeks of acclimatization, A1 – A3 were injected with 1.5 ml of 106 cfu/ml of A. hydrophila, P1-P3 were injected with 1.5 ml of 106 cfu/ml of P. aeruginosa, while C1-C3 were pathogen free. At the end of the experiment, it was observed that there was a constant increase, in the enzyme activities of the infected fish, indicating increase in virulence with respect to weeks of exposure but P. aeruginosa had higher pathogenicity compared to A. hydrophila.