How to reduce injuries and deaths of induced-spawning broodstock? Analysis of key techniques

The main factors causing injuries and deaths of induced-spawning broodstock: First, broodstock consume a great deal of physical energy during the spawning and reproduction process, and coupled with the side effects of spawning-inducing drugs, the body's resistance of the broodstock declines; if the fish body is injured and pathogens invade, disease is easily triggered. Second, poor physique of the broodstock, or a large fluctuation in water temperature during induced spawning, or improper dosage of spawning-inducing drugs, etc., can prevent the broodstock from spawning normally, and this in turn causes a disorder of their own physiological activities and leads to death. Therefore, in production, we must not only effectively carry out the pre-spawning rearing of broodstock so that the gonads of the broodstock develop normally and mature and the fish have a robust physique, but also pay attention to induced-spawning operations and post-spawning care.

First of all, attention must be paid to fishing operations.

Whether seining broodstock from a broodstock pond or from a spawning pond, the netting action must be quick and coordinated; as soon as the net approaches the bank, it should be closed quickly, and broodstock must be prevented from colliding with the pond wall and being injured. On clear days when the temperature is relatively high and the fish transport distance (the distance between the broodstock pond and the spawning pond) is relatively long, it is best to choose early morning or evening for seining, to prevent the broodstock from suffering oxygen deprivation and injury inside the fish-carrying stretcher. Broodstock with a good physique and appropriate gonadal maturity should be selected for induced spawning, and high-dose drugs should not be used for induced spawning.

Second, broodstock after induced spawning must be checked one by one.

For any female broodstock with a distended abdomen, the abdomen should be gently pressed by hand to help it release the mature eggs already inside its abdomen. If the broodstock suffers from difficult labor because the genital pore is blocked, a sterilized scalpel or scissors can be used to cut and enlarge the blocked genital pore so that the mature fish eggs can be discharged from the body; this can prevent the mature eggs from absorbing water and swelling inside the broodstock's abdomen and endangering the broodstock. For any broodstock with wounds on the body surface, first wipe the wound dry with absorbent cotton, then apply and wash the wound with potassium permanganate solution or iodine tincture, etc., and then use a finger to smear sulfonamide antibacterial and anti-inflammatory ointment on the wound from the tail of the broodstock toward the head against the direction of the scales. Broodstock after induced spawning, regardless of whether they are injured, must be injected with an appropriate amount of anti-inflammatory drugs.

Third, the pond where broodstock are stocked after induced spawning must first be cleared and disinfected with quicklime.

The pond water for stocking must be fresh, and a water depth of about 1.5 m is appropriate. For the first month after the post-spawning broodstock are released into the pond, it is best not to apply organic manure, and regular disinfection and sterilization should be carried out. About 5 days after release into the pond, feed such as germinated grain, malt or bran cake that the broodstock like to eat can be provided; for grass carp, an appropriate amount of fresh tender green grass can be provided. Generally, a small amount of fresh water should be replaced every 3 to 5 days to stimulate the appetite of the broodstock and help them recover quickly.