A cross-sectional study was conducted from October 2016 to May 2017 on Oreochromis niloticus, Cyprinus carpio and Clarias gariepinus fish species at Lake Hayiq, North East Ethiopia with the objective of isolation and identification of major gram-negative bacterial pathogens of commonly catched fish species from Lake Hayik. A total of 98 live fishes (49 Oreochromis niloticus, 30 Cyprinus carpio and 19 Clarias gariepinus) were collected and transported to the laboratory. From the three fish species a total of 384 organ samples (96 skins, 98 gills, 94 intestines, 33 swim bladders, 19 kidneys, and 44 livers) were taken. A systematic random sampling technique was used to select the fish samples after drawn from the water. Among 384 fish organ samples 116 (30.2%) gram negative bacterial isolates were found: 9 (2.3%) Aeromonas species, 24 (6.3%) Pseudomonas species, 6 (1.6%) Enterobacter species, 29 (7.6%) Escherichia species, 4 (1.6%) Edwardsiella species, 11 (2.9%) Klebsiella species, 5 (1.3%) Proteus species, 8 (2.1%) Vibrio species, 14 (3.6%) Flavobacter species and 6 (1.6%) Salmonella species were found. Isolation among organs: Pseudomonas species, skin (33.3%), intestine (33.3%), and swim bladder (12.5%); Escherichia species: intestine (41.4%), skin (24.2%) and gill (24.2%) and Klebsiella species: liver (27.3%), gills (36.4%) were found. All the isolated bacterial species were gram-negative bacteria. From the three fish species, Oreochromis niloticus was the most affected fish species (48.2%) while Clarias gariepinus species were the least affected species (17.2%). In conclusion, majorities of those pathogens isolated and identified were very important for different fish disease outbreaks and also public health importance. But, very few and disintegrated studies with scanty data have been done whereas, it has been nowadays fishery is one of the main growth transformation plan for food security in Ethiopia. Therefore, it needs further integrated investigation on fish bacterial diseases.

Isolation and identification of pathogenic fungi from African Catfish (Clarias gariepinus) eggs and adults in Ethiopian National Fishery and Aquatic Life Research Center hatchery was conducted from October 2015 to May 2016. The aim of this study was to investigate the aquatic fungal flora associated with eggs and brood stock from African catfish in the center. A total of 16 egg samples, 77 swab samples from skin of adult fishes (brood stock) and water samples from 14 incubating containers were investigated. Samples were collected from water, outer body surface of fish as well as from artificially hatched eggs. Isolation and identification of the fungus was done on colonial and microscopic characteristics. In this study, 84.11% samples were positive for fungal growth and fungus isolates belonging to seven different genera were identified. Tricophyton, Saprolegnia, Rhizopus, Penicillium, Mucor, Microsporum and Alternaria were among the dominant isolated fungal genera. Among the isolated genera, Tricophyton was detected from 13.08% of the samples, while Alternaria had the least with 3.74%, unidentified fungi accounts for 14.02% and unidentified yeast were 20.56%. Based on the results, various pathogenic fungi species were identified from fish body, water and hatched eggs, hence are potential causes of mortality and decreased egg hatchability. In the light of this, appropriate egg and water disinfection methods are essential for hatchery management. Fishes in rearing facilities must be given proper health management monitoring to prevent outbreak of fungal disease.