Effects Of Space,Gender And 5-HT On The Aggressive Behavior Of Chinese Mitten Crab(Eriocheir Sinensis)

Chinese mitten crab(Eriocheir sinensis)is one of the most important freshwater aquaculture species in China.During the breeding process,the aggressive behavior of Chinese mitten crab is widespread,causing great losses to the breeding.It is aggressive behavior that can render it possible for Chinese mitten crab to decrease feeding rate,energy consumption,injury and even death of animals.At present,with the increase of the density of Chinese mitten crab,the residual limb rate and mortality rate are also increasing.In order to improve economic efficiency,reduce the rate of residual limbs and improve breeding survival rate is the key.So it is so necessary to understand the characteristics and occurrence of the aggressive behavior of Chinese mitten crab.This study used Chinese mitten crabs as research objects.,and its aggressive behavior and influencing factors were analyzed to provide guidance for the culture of Chinese mitten crabs.In this study,the behavior of juvenile Chinese mitten crab is observed by video recording.The characteristics of aggressive behavior of juvenile Chinese mitten crab are analyzed,and we explore the influence of tank size,gender and size on aggressive behavior.The results show that juvenile Chinese mitten crabs of different genders have different density thresholds.When the tank size is d=15cm,the number of attacks by males is significantly less than that of the other three tank size(P < 0.05).The aggressive intensity of male crab is higher than that of female,and the ratio of aggressive intensity of 3 points and 4 points was significantly higher in males than in females(P < 0.05).There is no significant difference in contest duration and contest number between the three size juvenile Chinese mitten crab(P > 0.05).The results show that mixed sex storage is better than single sex storage model,keeping appropriate storage density,and keeping juvenile Chinese mitten crab separately according to their body size can reduce aggression behavior.The effects of 5-hydroxytryptamine(5-HT)on the aggressive behavior of Chinese mitten crab are analyzed by exogenous injection.The results show that the 5-HT concentration of hemolymph of Chinese mitten crab increase significantly after the aggression behavior,and reached a peak after 0 hours.The winner is 142.428pg/ml,and the loser is161.476pg/ml.With the increase of time,the 5-HT concentration of hemolymph decrease gradually;What' more,in the study,we find that the concentration of 5-HT of the losers is always higher than that of the winners,and the 5-HT concentration of the crabs return to normal level after 12 hours;The number and duration of aggression behavior of crabs which are all injected 5-HT are less than the other three groups,but the difference is not significant(P > 0.05);The number and duration of aggressive behaviors which get 3 and 4 points in thegroup that only one crab is injected with 5-HT and both crabs are injected with 5-HT were significantly less than the other two groups(P < 0.05).After 5-HT injection,the concentration of 5-HT in hemolymph gradually decreased,and returned to a stable level after 2 hours,there was no significant change in the saline injection group.