When do koi fish fry change color?

Koi fish fry generally begin to change color after half a month, but the color is lighter. After a while, the color will be clearer and patterns will appear. The fishing ground began to select koi fish fry one month after the koi fish was released every year. Koi fish's excellent characters are all bred by hybridization. Gene recombination may lead to mutation in the breeding process, leading to "fading" and "blackening", which is difficult for ordinary breeding enthusiasts to control due to genetic factors.

There is a body color transition period from juvenile to semi-adult fish in koi fish, which is also a key period for the formation of fish quality in koi fish. In the meantime, it needs careful feeding and careful management.

Extended data

Key points of breeding

1, environmental requirements

Koi fish, like goldfish, has no strict requirements on water temperature and water quality. The suitable temperature range is 2℃ ~ 30℃, but it can't resist the sudden change of water temperature and the discomfort of koi fish when the temperature difference suddenly exceeds 2℃ ~ 3℃. The optimum water temperature is 20℃ ~ 25℃. It needs sufficient oxygen and is suitable for living in a slightly alkaline and low hardness water environment.

2. Feeding requirements

Koi fish is an omnivorous fish, which can eat mollusks, fragments of higher aquatic plants, benthos, even tiny algae or synthetic granular bait.

3. Selection of fish species

Fish species with healthy fish body, no damage, no desquamation and other diseases, bright fish body, various colors and clear boundaries should be selected.

4. Feeding density

Common carp is a highly adaptable fish, and koi fish has retained this characteristic. They can be raised anywhere from fish tanks to outdoor ponds, and they will soon grow to 30 cm or more, so it is worse to use traditional indoor fish tanks than round plastic pots. Koi fish is a cold-water fish, so it is best to raise koi fish in a hot place with a water depth of more than half a meter in summer.

For general stocking of fish ponds, please refer to the koi fish density table for stocking fish ponds; The density of the aquarium is generally 60 cm× 30 cm× 15 cm, and six koi fish with a body length of 15 cm -20 cm can be raised. 90 cm× 30 cm× 50 cm can stock 8 tails; 110cm× 30cm× 50cm can be stocked10 tail.

5, bait feeding

Koi fish is an omnivorous fish. It is best to feed it with synthetic granules, bait, bean cakes, vegetable cakes, bread crumbs, fish worms, clams, crab meat, radishes and duckweed. It is best to feed the fish regularly to avoid the stress reaction of the fish.

6. Four seasons management

With the change of seasonal temperature, the management methods in koi fish are different.

In spring, when the weather is warm and cold, koi fish begins to recover from hibernation, and the breeding moves from indoor to outdoor. However, special attention should be paid to sudden cooling, timely mulching and keeping the water temperature stable. Plant bait is the main food, and the dosage is gradually increased from less to facilitate the digestion and absorption of koi fish.

When the weather is hot in summer, it is necessary to cover the plastic sunshade net to prevent direct sunlight, and it is most appropriate to reduce the sunlight illumination from 8000 ~ 12000 lux to 5500 ~ 5800 lux.

In autumn, the weather is less rainy and sunny, and the water temperature drops obviously, which is most suitable for the growth of koi fish and can increase the proportion of animals (protein), such as silkworm chrysalis. Increase investment and promote rapid growth.

In winter, the weather is cold. When the temperature drops to 0℃, koi fish should be moved to an indoor fish pond for wintering, and the indoor water temperature should be kept at 2℃ ~ 10℃. Pay attention to keep warm, feed properly and prevent diseases. The wintering period in koi fish is 1 1 to March of the following year.

7. Distinguish between men and women

Mature koi fish can identify gender in the following three ways.

Look at the picture: Abdominal hypertrophy is female; The slender figure is male.

Look at the anus: the anus is wide and flat for women; The man with small anal invagination is a man.

Look at idolization: when the male is about to ejaculate, a small reproductive tumor will grow on his head and pectoral fin, which is idolization. In the breeding season, all those who are not worshipped are females; Idolization is a hero. Touch the fin with your hand. If there are rough horny protrusions, it is a male fish. Smooth is a female fish. When a mature male fish gently presses his abdomen, white semen will flow out.