How to distinguish the males and females of the four major domestic fish-herring, grass carp, silver carp and bighead carp?

There are many kinds of fish, and many fish can easily distinguish between male and female from the various characteristics of their appearance, but there are also many fish that are difficult to distinguish between male and female by their appearance. How can the four major domestic fish-herring, grass carp, silver carp and bighead carp be distinguished between male and female?

For the male and female identification of Sijie fish: in the reproductive season, it is mainly judged according to the appearance and accessory sexual characteristics of the rapid gonadal development of the parent fish, for example, the abdomen of the mature female fish is obviously larger than that of the male fish, and the cloacal pore of the female fish is slightly protruding and slightly ruddy, while the male fish's abdomen is small, and light pressure can extrude white semen. In the non-reproductive season, males and females are identified mainly by the shape and length of the pectoral fins. Generally speaking, the pectoral fins of males are narrow and long, while those of females are relatively short and fan-shaped. The details are as follows:

1. Herring

The main results are as follows: (1) male fish: when the gonads are well developed in the reproductive season, chasing stars appear on the inside of the pectoral fin and on the operculum, and there are 6-9 connected bony hard scales on the inferior lateral line scales of the dorsal fin in the non-reproductive season.

(2) female fish: when the gonad is well developed in the reproductive season, the pectoral fin is smooth and there is no chasing star; in the non-reproductive season, there is no bony hard scale on the lateral line scale below the dorsal fin.

2. Grass carp

The main results are as follows: (1) male fish: when the gonads are well developed in the reproductive season, chasing stars appear on the inside of the pectoral fin and the operculum, and there is a rough feeling with hand stroking; in the non-reproductive season, the pectoral fins are longer and thicker, especially the I ~ II fins are longer, naturally open in the shape of a sharp knife, and can cover more than 7 large scales when close to the fish body.

(2) female fish: in the reproductive season, there is generally no star pursuit or a small amount of star pursuit on the pectoral fins; in the non-reproductive season, the pectoral fins are thinner, in which the I ~ IV fins are longer and naturally open slightly fan-shaped, and the pectoral fins cover only 6 large scales when they are close to the fish body.

3. Silver carp

(1) male fish: in the non-reproductive season, there is a row of bony fine pectinate teeth on the inside of the front fin of the pectoral fin, especially on the first fin. Touch with the fin, there is a rough prickle feeling, these pectinate teeth will not disappear after growth.

(2) female fish: the pectoral fin is relatively smooth, and some pectinate teeth are found in the middle and lower part of the pectoral fin of some fish.

4. Bighead carp

(1) male fish: in the non-reproductive season, the pectoral fins have backward sloping blade-like protuberances on each of the upper edges of the front fins, which can be felt by touching them laterally with their hands.

(2) female fish: the pectoral fins are smooth and there is no sense of cutting hands.