Parasitic diseases and pests
Aquaculture environments that are suitable for growth and reproduction of cultured animals are also hospitable to potential disease agents such as parasites. It is no wonder then that fish mortalities and abnormalities associated with parasites as disease agents are well documented, indicating their importance in aquaculture.
The study of parasites involves an understanding of certain existing relation-ships in a particular population. Symbiosis or “living together” is a relation-ship that benefits one or both parties. In commensalism, no party is harmed and both could live without the other. Mutualism is a relationship where both parties benefit from each other, and neither could live without the other. Para-sitism is a one-way relationship in which one party (the parasite) dependsupon, and benefits from, the other partner (the host), biochemically and physi-ologically.
Parasites live in a variety of environments. Those that live on the external sur-faces (skin, fins, gills) of the host are called ectoparasites, while those found in the internal organs are called endoparasites.