Artificial Breeding Techniques for Taiwan Loach

A. Natural breeding method for Taiwan loach. After the beginning of spring, repair the fish pond, disinfect it with quicklime, then fill with fresh water. After the medicinal effect of the pond water has dissipated, place the brood fish into the pond at a female-to-male ratio of 1:2, at about 300 g per sq m. When the pond water temperature rises to about 20°C, place spawning nests made of palm fiber, willow rootlets or aquatic plants in the pond. After placing the spawning nests, check and clean the mud and dirt on them frequently, so as not to affect the adhesion of the eggs when the Taiwan loach spawns. Taiwan loach prefers to spawn during thunderstorms or when the water temperature suddenly rises. Spawning mostly begins in the early morning and ends at around 10 a.m.; the spawning process takes 20 to 30 minutes. During spawning, the brood fish chase each other vigorously; at the peak, the male loach wraps its body around the front belly of the female loach, completing the spawning and fertilization process. After spawning, promptly remove the spawning nests with eggs attached and transfer them to another pond for hatching, to prevent the brood fish from eating the eggs. At the same time, add new spawning nests so the brood fish that have not yet spawned can continue to spawn. The spawning pond must be protected against snakes, frogs, rats and other hazards to the brood fish.

B. Artificial breeding method for Taiwan loach. Artificial breeding of Taiwan loach is the same as that of domestic fish. The types and doses of oxytocin used, calculated per female loach, are: carp pituitary 0.5 to 1, or frog pituitary 2 to 3, human chorionic gonadotropin 100 to 150 international units, or analog (LRH-A) 5 to 10 micrograms. The dose for male loach is halved. The solvent injection volume is 0.1 to 0.2 mL, injected with a 1 mL syringe and a No. 4 needle. The injection site is the midline of the abdomen between the pectoral and pelvic fins, or intramuscular injection in the back. Because Taiwan loach likes to burrow and move, it can be wrapped in warm gauze during injection (exposing the injection site). After injection, place them in the spawning pond; the subsequent work is the same as for natural breeding. At a water temperature of 20 to 25°C, they will come into spawning condition and spawn after 10 to 20 hours. If artificial insemination is used, the male and female Taiwan loach that have been injected with oxytocin can be temporarily kept separately in small ponds or cages; at a water temperature of 18 to 25°C, after 10 to 15 hours, eggs will flow out when the female loach's abdomen is gently pressed, and artificial insemination can then be carried out by the dry method. The operating method and precautions are the same as for domestic fish. After artificial insemination, the eggs are immediately placed on the nests. The method is: take a bucket of clear water, spread the spawning nest flat on the bottom of the bucket, then one person gently shakes the spawning nest while stirring the water, and another slowly pours the eggs into the bucket, so that the eggs are evenly attached to the nest. After being attached to the nest, transfer them to the hatching pond for hatching. The fertilized eggs of Taiwan loach can hatch normally within a water temperature range of 20 to 30°C, and generally the fry can hatch in about 2 days. Using a small container with still water and changing the water frequently (2 times a day) gives very good hatching results. It is suitable to place 400 to 600 eggs per liter of water. During hatching, shaking must be avoided; during hatching, a 0.1×10-6 malachite green solution can be used for disinfection to prevent parasitic water mold. Newly hatched loach fry cannot move freely and attach to the spawning nest or other objects with their heads, using the yolk as nutrition. Fry hatched in the pond are generally kept in the original pond for rearing, with the water depth kept at 20 to 30 cm, and a density of 500 to 1500 per sq m is suitable; if too dense, some fry should be removed and reared in another pond. Loach fry begin feeding 3 days after hatching. At this time, feed cooked and crushed egg yolk or fish meal suspension several times a day, with the feeding amount limited to what is eaten within 1 hour. After 2 to 3 days, switch to feeding water fleas, rotifers, chopped tubifex or silkworm pupae, etc. After about 10 days of rearing. After about 1 month, when the fry have grown to around 3 cm, transfer them to a fingerling pond, or they can be directly placed into rice fields, ponds or pits for adult fish rearing. The area of the fingerling pond should preferably be 30 to 50 sq m. Before stocking, the pond must be cleared and disinfected, and base fertilizer applied to cultivate food organisms. The stocking amount is about 30 g per sq m (800 to 1000 fish). Within half a month after the fingerlings are put into the pond, feed plant-based feed twice a day, at 3% to 5% of the fish body weight. In summer, when the pond water is shallow and the water temperature is high, always pay attention to changes in water quality and change the water frequently. When the fingerlings grow to 8 to 10 cm, they enter the adult fish rearing stage.