Parasitas in tilapia of nile in fresh water net-tank system

Abstract

Tilapia fish are native from Africa which, due to their optimum characteristics, such as genetic plasticity, rusticity, commercial easiness, amongst others, should be included as the most important species of fish commercially bred. It can be bred in earth pounds with low water renovation or systems such as raceways and net-tanks, which present a high water renovation. A variety of parasitic agents can cause problems in tilapia breeds, none of them seeming to be specific to these fish. Filo Ciliophora protozoa such as Trichodina sp., Ichthyophthirius multifilis, Ambiphyra sp.,Apiosoma sp., as well as monogeneans can cause problems in tilapia breeding. Among the protozoan, the Trichodina sp and the I. multifilis are of great importance, mainly in severe infections when the environment is favourable for their reproduction, causing despoilment in the gill epithelium and skin of fish, predisposing it to respiratory problems and secondary infections. Monogeneans can also bring serious problems mainly in tilapia alevins raised in super-intensive systems. Eutrophized environments with excessive organic matter are favorable for the maintenance and reproduction of these parasite as well as the protozoa. Severe monogenean infection can cause harm to the animals because of its particular mode of fixing itself on the host through hooks and anchors, causing reactions of the host that can be harmful for its breathing activity.