ROLE OF STOCKING DENSITY AND ABIOTIC FACTORS OF POND ON PROPAGATION AND DISTRIBUTION OF MONOGENETIC GILL PARASITES IN FARMED ROHU, LABEO ROHITA (HAMILTON) -A STUDY

In farm, monogenean infection occur by mixed species and here occurrence and distribution of monogenetic gill parasites were studied with an objective to evaluate the potentiality of monogeneans to propagate in farmed Indian major carp, rohu (Labeo rohita) under different stocking density (low, medium and high). Sampling of water and fish was done fortnightly and soil sample on monthly basis for about six months. Four species of monogeneans were observed. Pond with highest stocking density showed 100% prevalence throughout the period and rest showed sporadic as well as no infection pattern. Study of spatial distribution showed 1st, 2nd and 3rd gill arches had higher distribution of monogeneans than the 4th one. The posterior section of each gill arch had maximum monogenean intensity as compared to the anterior one. The mean intensity of parasites was significantly greater in higher size class of rohu. Dissolved oxygen and soil organic carbon show significant (p > 0.05 and p > 0.01) positive correlation with parasite intensity and prevalence respectively. The results suggest that the propagation of gill monogeneans is positively influenced by higher stocking density, organic load and dissolved oxygen and these factors don’t influence their distribution pattern in gills.