Aggressive behavior variation and experience effects in three families of juvenile Chinese mitten crab (Eriocheir sinensis).

To assess how variable is the aggressive behavior among families (A, B, and C) and the experience effect of fighting among juvenile Chinese mitten crab (Eriocheir sinensis), we performed a total of 36 pairs of intrafamily and interfamily contests between three families of Eriocheir sinensis, qualifying and quantifying their aggressive acts and 13 pairs of winners within family and between family A and B. A table of aggression intensity was established, ranging from 1 (chasing) to 4 (intense combat). Crabs of intrafamily association performed more aggressive acts of shorter duration than interfamily, family B was more aggressive than those from families A and C: family C was the least aggressive, which is also the most morphologically distinct strain (a new strain with a red carapace). During the second fighting trail, the intensity and number of fights were significantly different to first fight conditions and also differed among families. Therefore, our results suggest that the aggressive behavior of Eriocheir sinensis is different among different families, and the combat experience has a significant effect on the secondary fight. This is the first report of aggressive behavior in Eriocheir sinensis, a reference for crab aquaculture and provides new ideas for genetic breeding work in crab selected breeding programmes. It will be possible to carry out more profound studies of the behavior of these animals.