The larvae are small, so for the convenience of management, the number of larvae in the aquarium can be correspondingly more, as long as it doesn't feel crowded. When larval fish can swallow small fish worms, the body development speed is obviously accelerated. Because of individual growth, the limited space feels crowded and the stocking density is slightly higher. If you can swallow larger fish worms, the larvae will grow faster and then enter the juvenile management.

In view of the rapid growth and development of juvenile fish, the stocking density of single cylinder should be adjusted in time according to the individual growth speed of juvenile fish at different stages of growth.

Generally, an aquarium of 50cm× 30cm× 30cm, taking angelfish as an example, can initially stock 500 ~ 1000 larvae. If you choose 100 cm× 50 cm× 45 cm fish tank, you can raise 500 ~ 800 young fish. If more than 1000 fish are stocked, it is often due to the crowding among individuals, and the uneven feeding of fish will lead to uneven individual development, or each fin of young fish will be damaged and deformed.

When the stocking density is too high, the young fish often float their heads due to lack of oxygen, and the uneven feeding of young fish leads to uneven individual size and level in the fish school, which makes the feeding water extremely turbid, reduces the transparency of water quality and slows down the development of fish. When the stocking density of juvenile fish in aquarium is too low, the juvenile fish grows rapidly, which has no adverse effect on fish development, but the output value per tank is slightly lower and the economic benefit is poor.

Gain weight:

In the juvenile stage, the bones of fish grow and develop rapidly, with great activity and food intake, and the daily demand for bait also increases obviously. The feeding standard of young fish should be that the fish and worms fed each time can be eaten within 10 ~ 20 minutes. The number of feeding should be controlled at about 2 ~ 3 times a day, and the amount of feeding should be kept full every time. Young fish feed on fish worms. If the feces of young fish are black or light gray after eating, it indicates normal digestion. If the feces are milky white, it means that the fish has indigestion, and the feeding amount should be reduced at this time. The appetite of young fish will also be partly affected by water environment, such as water temperature, water quality, dissolved oxygen and so on. Therefore, the daily feeding amount should also change slightly. In addition, the feeding amount of juvenile fish is also related to the stocking density in the aquarium. The higher the stocking density, the greater the feeding quantity.

Different species of tropical fish have different individual sizes of parent fish, indicating that the growth rate of juvenile fish is different. The individual size of one-month-old young fish is obviously different. Some small species of young fish can only eat small fish worms when they are one month old, while large species of young fish can already eat big fish worms. Therefore, the bait of young fish can also be classified by different mesh numbers according to the size, and then the young fish of different sizes can be fed separately to meet the palatability of the bait of young fish, and the feeding amount should be sufficient, and feeding cannot be stopped.

Use of water:

Because tropical fish have a strong appetite in the juvenile stage, the metabolites also increase. After a few days, many organic substances such as residual bait and feces at the bottom of the aquarium consume oxygen in the water, which is easy to spoil the water quality. If the bait remains too much, a layer of dead fish and worms will be seen at the bottom of the aquarium, and the water will be milky white. Therefore, it is necessary to change the feeding water in the aquarium regularly. Replace new water by adding water. Gently insert a short glass or metal tube into one end of a rubber tube or a plastic tube with a diameter of 3-4 cm, extend into the bottom of the aquarium, and move slowly along the bottom of the tank. Based on the principle of cylinder suction, all the dirt at the bottom of the cylinder can be sucked out, and then fresh water with the same temperature and property can be selected and injected slowly along the cylinder wall.

Under normal circumstances, the feeding water for young fish should be changed periodically every 2 ~ 3 days. In the late growth period of young fish or when young fish eat too much, you can change some feed water every day. The purpose of changing water is to keep the water quality stable and the water color clear and transparent, and at the same time stimulate the metabolic activities of young fish and promote the growth and development of the body. When the water quality deteriorates, we can also consider replacing all the water supply. At this time, 1 ~ 2 tablets of oxytetracycline can be put into fresh water to prevent diseases caused by unsuitable water change for young fish. All young fish change water in the same way as young fish.

Temperature adjustment:

The daily water temperature of young betta fish, especially the individuals in the late growth stage, is basically the same as that of adult fish. The constant temperature of tropical fish is relative. The daily feeding water temperature of most tropical fish can be controlled at about 25℃, and the maximum temperature difference per day should not exceed 2℃. This change should be made gradually. For example, if 1 ~ 2℃ changes in a short time, young fish will easily get sick. Therefore, the change of water temperature of young fish should be prevented from being hot and cold. The growth of young fish should not only pay attention to the regulation of water temperature, but also need to change feed water regularly.