Grass goldfish is best to feed. Grass goldfish is the most common and best-raised goldfish species, also called golden crucian carp, which is the ancestor of goldfish. As a wide-temperature fish, it can survive in the environment of 0-39 ℃, but it can adapt to the temperature of 20-28 ℃. Because of its miscellaneous food habits, there are many foods to choose from, and ordinary fish food is also eaten, so it is not very picky eaters. In addition, it does not require high dissolved oxygen, and if the feeding density is not large, it does not need oxygenation.

1. Guppy: Guppy is a common small tropical ornamental fish with a large tail and gorgeous color, just like peacocks. This kind of fish is easier to raise, because compared with other tropical fish, it can endure the low temperature of 16 ℃, but it is better to control the temperature within 20-30 ℃, so that it will be in better condition.

2. Koi: Koi is a large fish, which can't be raised in general fish tanks. As a fish that inherits the characteristics of carp, its vitality is particularly strong, so it is easier to raise. However, it should be noted that this kind of fish still has certain requirements for oxygen content in water, so it is best to prepare an oxygen pump and fill it with oxygen every day.

3. Zebrafish: Zebrafish is also a small tropical fish with many kinds and colors, which is very good-looking and easy to raise. This kind of fish has a gentle temperament and will swim in the tank all the time. It does not require high water quality. It is enough to keep the temperature above 20 ℃. Some pebbles can be put in the tank to help make the water clear.