Three amoeba species were isolated from 3 out of 193 farmed tilapias,
Oreuchromis niloticus (L.), screened for the presence of free-living a
moebae in parenchymatous organs. Hurtmannella vermiformis Page, 1967 a
nd Rosculus ithacus Hawes, 1963 were isolated from the kidney tissue.
The third strain isolated from the liver shared morphological features
of Mayorella and Platyamoeha spp. and therefore its taxonomic positio
n has not been determined as yet. Pathogenicity of cloned strain of H.
vermiformis was proved in two fish hosts.