Food and Feeding Habits of an Introduced Mosquitofish, Gambusia holbrooki (Girard) (Poeciliidae) in a Subtropical Lake, Lake Nainital, India

The feeding ecology and diet composition of an introduced mosquito fish, Gambusia holbrooki was studied in Lake Nainital for a period of one year from February, 2005 to January, 2006. The study confirmed the zooplanktivorous nature of the fish. The fish showed preference towards cladocerans, though copepods and insects also formed the significant proportion of its diet. Mosquito larvae constituted a negligible proportion of its diet. There was no significant variation in diet composition of males and females; however, diet of juvenile fish differed significantly from adults. Significant temporal variations also occurred in the diet composition of adults and juvenile fish. The study also revealed the positive relation between fish size and prey size selection. Higher values of fullness of gut were found for juvenile fish than that of adult Gambusia.