The direct effects of this parasite on its host depend on the number of parasites and the size of the host. One or two parasites on a small fish cause the local damage on the epithelia. Several parasites have a very significant effect. Fish with heavy infestations become lethargic, can cease feeding and show a general deterioration in their condition as reduced pigmentation, fins drooping (Lester and Roubal 1995).
As well as the damage and stress caused by Argulus itself, one of the main worries for fish producers is the associated secondary infestations that can result from infestations with parasite. Several studies have examined the role of parasites as vectors for other diseases such as Aeromoniasis or Pseudomoniasis (Bauer 1991, Richards 1977).
There are many methods of control, prevention and treatment of argulosis (Puffer and Beal 1981, Kabata 1985, Singhal et al.. 1986, Poulin and FitzGeral 1987, Gault et al.. 2002, Hakalahti et al.. 2004).
In this study, A. foliaceus infestation of tiger oscar (A. ocellatus) and their treatment is discussed.