THE FEEDING BEHAVIOR OF GRASS CARP (CTENOPHARYNGODEN IDELLVS) ON DIFFERENT TYPES OF SUBMERGED PLANTS

Here we studied the feeding behaviors of grass carp on different types of submerged plants including Hydrilla verticillata, Vallisneria natans, Potamogeton crispus, Ceratophyllum demersum and Myriophyllum spicatum, and we examined the feeding selectivity and feeding rate of grass carp with different weights (35, 45, 55, 65, 75 and 85 g) and community densities (1.2, 2.4, 3.6 and 4.8 g/L). We found that the order of feeding preference of grass carp was: H. verticillata V. natans P. crispus C. demersum M. spicatum. Regardless of the fish weight grass carp preferred feeding on H. verticillata, followed by V. natans, C. demersum and M. spicatum. We also found that the daily feeding rate of small grass carp was higher than that of big individuals. The competition on submerged plants was obvious in the presence of H. verticillata, and the feeding rate decreased along with the increase in community density when the water quality deteriorated.