1. stocking density: rectangular aquariums in China should not be raised more, but less should not be raised more. For example, in a container 40 cm long, 25 cm wide and 30 cm high, you can raise 6-8 small fish 5-7 cm long. For example, a round glass jar with a diameter of 26 cm and a height of 13 cm can raise 4 ~ 6 small goldfish with a diameter of 4 ~ 6 cm. Adult fish with a body length of more than 8 cm should not be kept in small glass tanks, but in luxurious large glass tanks or ceramic tanks, and equipped with small oxygenators for standby to prevent hypoxia. These stocking densities are only reference figures, but also depend on the level of water temperature, the strength of fish and the quality of water, which cannot be determined mechanically. Generally speaking, there are large fish and few animals. Raise more in winter and less in summer; You can raise more when the water temperature is low, and raise less when the water temperature is high.

2. Feeding: Feeding is rich in animal feed and white sesame seeds. Animal feed, such as Daphnia, earthworm, Tenebrio molitor, caterpillar, dust mite, etc. Mainly feed earthworms and sesame seeds. Both red earthworms and black earthworms can be fed. Don't feed inferior goldfish feed. Because this feed has too much starch, poor nutrition and difficult digestion, it is easy to pollute the water quality. If fish is malnourished, it will grow slowly and get sick easily.

3, lighting: it is best to put the fish tank in a sunny place 1-2 hours. In this way, ultraviolet rays in sunlight are used for sterilization. Try to prevent fish diseases, supplemented by drug treatment. At the same time, due to photosynthesis, the color of fish is more bright and beautiful.

4. Change water: Changing water frequently can increase dissolved oxygen in water. When changing water, you can only change one-third to one-quarter, and you can't change a lot at once. The fish can't adapt. It is very important to keep the water quality of the aquarium clear. There is enough dissolved oxygen in the water to make fish grow and grow fast. Otherwise it will stop growing or even die.