Fish keeping isconsidered an important source of entertaining activity as people keepornamental fish as pets. On the other hand fish is also a valuable protein sourceto diet.
Recently aquaculture has become more focused to parasitic infectionsin fish because parasites seriously affects their yield and quality of life (Kennedy1994). Fish serve as a host to number of parasites. Parasiticinfestations in fish enhance the threat of predator attacks if the theirappearance, fitness or behavior is changed (Poulin et al.2005). Lernaea are freshwater parasites and aresource of severe disease in fish. Lernaea is termed ‘anchor worm’ due to itsanchor like cranial parts by which they attach under the skin of the fish andthey can be found in both wild-caught and cultured fish. Lernaeid copepods are verydetrimental parasites of freshwater fish.
Young fish are particularly susceptibleto this parasite as a small number of this parasite can kill them (Kabata 1982) (Molnár 1987).Lernaea infected fishpresent low levels of health due to metabolic disturbance, which in turn decreasestheir capacity to grow. Large-sized fish are mainly susceptible to adultparasites, because of the size of organisms and also by their way of access tothe host (Bhuiyan andMusa 2008). When small-sizedfish are heavily infested with Lernaeid in the copepodid stage, then theseparasites abolish gills, resulting in abnormal breathing and eventually causingdeath. Female parasites attach to the fish by using anterior anchor and embed profoundlyinto the fish body. The part of skin around the affection site becomes reddishand swells which may lead to hemorrhage and infection. Fish can bear smallnumber of parasites without any chief health issue but parasites act as a constantsource of irritation. Infestation finally results in inflammation of exaggeratedsite and often leads to secondary bacterial infection due to skin barrier disruption