INVESTIGATION OF DISEASES OF JUVENILE CATLA FROM CULTURE POND FARMING CONDITION IN MYMENSINGH

Abstract

Investigation on health conditions and diseases of juvenile catla (Catla catla) was carried out for clinical and histopathological observations from different farms of Mymensingh region.  A total of eight (8) farms, four Government (Govt.) and four Private (Pvt.) fish farms were selected for the study. The Indian major carp - catla was examined during June, 2010 to May, 2012. Monthly samplings were carried out with 5 fishes from each farm. Altogether 960 fish hosts were examined during the study period. Water quality parameters such as temperature, dissolved oxygen, pH, ammonia, hardness, alkalinity, transparency and depth of water etc. were taken and management practices were investigated fortnightly interval. These were almost similar for all experimental ponds. The risk of being infestation by parasites of catla significantly (p<0.001) increased when the water quality parameters were not maintained the optimum level. Clinical examination of fishes was also carried out for any kind of abnormalities at monthly intervals. For histopathological studies skin, muscle, gill, liver and kidney were collected, processed and stained in Haematoxylin and Eosin. Histologically, catla of different fish farms were more affected in colder months (October to January). Structures of fish organs were normal from March to July. In the months of September, minor pathologies were found to be started and in the months of February the pathological condition of fish gradually reduced. Pathological changes like necrosis, fungal granuloma, protozoan and monogenean cyst, vacuolation, melanomacrophase, haemorrhage, hypertrophy, hyperplasia and clubbing were recorded in all the investigated organs. Among them fish gills and skin were more affected followed by liver and kidney. Again when considered individual fish farm, fish of Pvt. Fish farms were more affected than others. The study showed that severity of clinically and pathologically changes were gradually increased in November to January. During the period mixed infection of protozoa, monogenea and argulus were noticed in catla of the investigated farms.