1, congenital malformation, caudal fin deformity rate is relatively high, degenerative deformity is very common; The deformity rate of dorsal fin is not high.

2. If the water is shallow, the dorsal fin cannot be opened; Tail fin is the main driving force of fish. As long as the fish can't swim fast, the function of the tail fin won't be too great.

3. If you are sick, the pectoral fin and dorsal fin are generally closed, and the caudal fin is generally not closed.