STUDIES ON THE DISEASES RESULTING FROM ENCYSTED METACERCARIOSIS IN SOME FRESHWATER FISHES

Abstract

This study was carried out on 200 freshwater fishes including 100

Oreochromis niloticus and 100 Clarias lazera. The results of these investigations could be summarized as follow: 1. The clinical picture revealed general emaciation, skin darkening with excessive mucus secreation, detached scales in scally fishes as well as white spots on skin of some fishes. The most characteristics black spots were also seen in skin and fins of naturally infected Oreochromis niloticus. Yellow to orange cycts present on the skin of some naturally infected Oreochr01nis niloticus. 2.The post-mortem findings of such fishes revealed variable sized

skin erosions and ulceration and variable sized grayish-white nodules in muscle and different internal organs, in Clarias lazera. Yellow to orange pea-sized encysted and exysted metacercariae arranged in a grape-like structure attached or embedded into branchiostegal musculature of Oreochromis niloticus. 3. The prevalence of EMC in examined fishes was 70% and 83%

among Oreochromis niloticus and Clarias lazera.

4. The seasonal prevalence of encysted metacercariae in Oreochromis niloticus was the highest in winter season (100%) followed by summer (92%), spring (60%) and the lowest was in autumn (28%) and the prevalence of encysted metacercariae among Clarias lazera was the same in winter, spring and summer seasons (84%) and followed by autumn (80%).