EFFECTS OF SEVERAL STIMULI ON FEEDING BEHAVIORS OF GIBEL CARP, CARASSIUS AURATUS GIBELIO

The two-ball method was adopted in a feeding trial, one test ball and the other control ball, to investigate the effects of several stimuli on feeding behaviors of gibel carp. Relative biting rates (compared with the control ball) were used to evaluate stimulative or suppressive effect of stimuli on feeding behavior of gibel carp, relative bites (compared with the bites of test ball of 10-5 mol/L alanine) to determine differences of effects of various chemical stimuli. Initial body weight of fish was (46.5?.3) g. L-aspartic acid, L-methionine, L-lysine, L-arginine, L-alanine, L-histine, betaine and lactic acid at the concentrations of 10-6-10-2 mol/L were tested for feeding stimuli in gibel carp, as well as 10-6- 10-2 g/L squid extracts. All responses of feeding behaviors were recorded from the second to the tenth minute after the experiment starting. The results showed that most of stimuli used in this study had no significant effects on feeding be-havioral responses of gibel carp. Aspartic acid at the concentrations from 10-6 mol/L to 10-4 mol/L had significant feed-ing stimulation in gibel carp, but weak repellent effects to feeding at concentrations of 10-3-10-2mol/L. 10-4 mol/L aspartic acid was the potential feeding stimulant of gibel carp, which average relative bites had 5.15 times of the 10-5 mol/L alanine. Another potential feeding stimulant was 10-4 mol/L arginine, which the average relative bites were 4.6 times of 10-5 mol/L alanine. There were significant dose-response relationships between the effects and the concentra-tions of arginine, betaine and lactic acid in gibel carp, and the highest relative bites of feeding behaviors in each stimu-lus were observed at the concentration of 10-4 mol/L, 10-5 mol/L and 10-5 mol/L, respectively. No significant difference was found in feeding responses of the other stimuli at the various concentrations. Based on the results of relative biting rates, most stimuli had no significant effects in stimulating feeding responses of gibel carp. Methionine and lactic acid were feeding repellents of gibel carp at the concentrations of 10-6-10-2 mol/L. 10-4 mol/L arginine, 10-5 mol/L alanine, 10-6 mol/L lysine, 10-3 mol/L lysine and 10-2 mol/L lysine had significantly stimulative effects on feeding behaviors of gibel carp. Except betaine and aspartic acid, most responses of stimuli were steadily in 2-9 minutes. Gibel carp adapted rapidly to the stimulating of betaine and aspartic acid at different concentrations, especially at 10-6-10-4mol/L.