Feeding Preferences and Digestive Physiology of Indian Carps in Polyculture Pond System

Catla (Catla catla), mrigala (Cirrhinus mrigala) and rohu (Labeo rohita) are commercially significant pond species in India. Despite being cultured for a long time in village ponds, sufficient information on the feeding preference and digestive physiology variables of these species in managed and unmanaged polyculture pond systems in India is not available. We carried out the gut content analysis and estimated the forage ratio for catla, rohu and mrigala species. The intestinal enzymes and liver glycogen were also estimated. Analysis of gut contents of C. catla indicated that the fish is herbivorous or phytoplanktivorous. Gut contents of L. rohita from all the ponds indicated it is Omniplanktivorus fish. In case of C. mrigala, the gut contents indicated that the fish is zooplanktivorous. Based on the results of digestive physiology, it can be inferred that consumable plant material would probably be exploited with the highest intensity by C. catla compared to L.rohita and with the lowest intensity by C. mrigala. On the other hand, animal components would be utilized more intensively by C. mrigala followed by L. rohita and with least intensity by C. catla. Digestive enzyme activity appeared to be comparatively higher in managed ponds. This study provides a deeper insight on the occupation of different feeding stratus by the three species of fish within the available food in polyculture arrangement allowing better understanding of how good production occurs and revealing that each species is focusing on a particular feeding stratus.