This study was conducted to evaluate the ability of motile Aeromonas species (MAS) to induce skin
lesions and cause mortality in African catfish (ACF). Eight motile Aeromonas isolates (A. hydrophila – 4
isolates, A. caviae – 2 isolates and A. sobria – 2 isolates) were used for the study. Ninety apparentlyhealthy
ACF juveniles were randomly assigned into 9 groups of 10 fish each. Fish in groups 1 – 4 were
infected with A. hydrophila while those in groups 5 – 6 and 7 – 8 were infected with A. caviae and A.
sobria, respectively. Infection was achieved by immersing fish in water containing 1x108 colony forming
units (cfu)/ml of experimental isolate. Fish in group 9 were immersed in water containing sterile
phosphate buffered saline (PBS) and served as the control. Fish in the infected and control groups were
monitored daily for 15 days for signs of ill health including development of skin lesions and mortality.
Skin lesions were processed for re-isolation of MAS. Skin lesions were found in 40 – 90% of
experimentally-infected fish while none of the uninfected had skin lesion. Mortality rate in infected fish
ranged from 20 – 90% while none of the uninfected died. Development of skin lesions as well as
mortality in the ACF was associated with experimental infection with Aeromonas isolates. This study has
shown that MAS could serve as the primary cause of skin lesions in cultured ACF.