Courtship habits of fish

Fish, like other vertebrates, during the reproductive season, when male and female parent fish enter the spawning grounds, they often go through a process of estrus and courtship. Male fish, in particular, will inevitably make various courtship movements when approaching female fish. But different species, methods of courtship, and the complexity of courtship actions vary greatly. Some male fish just swim around the female fish during courtship and show various states of sexual excitement; some also make various complex movements similar to the funny marriages of birds. However, this phenomenon only manifests during the union stage of the male and female, and at most lasts throughout the reproductive period. And when the act of procreation ends, the relationship between the sexes also ends.

For fish that spawn in the middle and upper layers of vast water bodies, most of the spawning broodstock reproduce in groups. These fish begin to come into estrus after arriving at the spawning ground. At this time, the male fish chases the female fish and is extremely active. Either the male and female fish appear side by side out of the water, or the heads of the male and female fish appear out of the water to swim, causing waves from time to time. When laying eggs, the female fish's abdomen faces upwards and her pectoral fins vibrate violently. This reproductive behavior is called "floating row" by fishermen. The "floating and discharge" phenomenon in silver carp's reproductive behavior is the most obvious. Other fish, such as bighead carp, grass carp, Chinese sturgeon, etc., are also represented. During the reproductive period, after the broodstock enters the spawning ovary, the male and female fish chase each other and are very active. The male fish in particular often jumps 2 or 3 feet out of the water, which fishermen call it "beach jumping." The number of fish such as grass carp, herring, silver carp, and bighead carp clustered in the spawning grounds is quite large, and since the sex ratio of the spawning fish group is close to 1:1, spawning activities are mostly carried out in pairs of male and female fish, and some There is a phenomenon of 2-3 male fish chasing one female fish.

Before spawning, crucian carp and carp often chase and play in pairs in shallow water grass. Sometimes the male fish's head hits the female fish's body, and sometimes it swims slowly sideways. After a period of time, the female fish turns sideways violently to lay the eggs, and the male fish tightly Then the semen is discharged. The golden catfish lays its eggs in the gills of river mussels. During the reproductive season, mature golden catfish often chase and swim together in pairs. When encountering river mussels, they show special excitement, and the ovipositing tubes immediately lengthen. Continuously swimming around the river clam. With the stimulation of the water flow from the mussel's outlet pipe, the female swims close to the mussel's outlet pipe many times, peeks and pecks at the mouth of the pipe, then tilts her body suddenly, aligns her long ovipositing tube with the outlet pipe, and quickly deposits her eggs. It is discharged into the gill cavity of the river mussel; the male fish injects the semen from the water inlet pipe immediately after the female fish spawns. When snakeheads lay eggs, the male fish builds a nest and enters the nest. By compressing the gill membrane, he makes a "cooing" sound to lure the female fish into the nest to lay eggs.

Qinghai Lake naked carps enter the spawning ground in groups, then divide into small groups to play in the water, and then several male fish chase one female. The dorsal and tail fins are often exposed from the water, and water splashes appear on the water. The male also butts the female's abdomen with his head and builds an egg nest with his anal and tail fins. When spawning, the male fish presses the female fish's tail with his head, often causing the female fish's head to emerge from the water, and turns her body over to ovulate, and the male fish then ejaculates. Most of the fertilized eggs that sink fall into the egg nest.

Many fish species reproduce in pairs. For example, when lampreys migrate from the ocean into rivers to spawn, they usually travel in pairs. The male fish first goes to the spawning site to choose a shallow, fast-flowing, gravel-bottomed water area, and digs a small groove with its abdomen. The female fish then arrives and completes the task of digging the nest together. The method of mating is very interesting. The female parent fish first uses her mouth to attach to the big stone on the nest, and the male parent fish uses his mouth to attach to the female's head. After that, the male fish wraps the female with the back part of his body, so that the male and female fish are together. Roll into a "twist" shape. Then, the male and female fish each violently vibrate the rear part of the body to stir up the fine yarn, and each releases eggs and sperm.

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