Guppy is a common small tropical fish. Because of its small size, it needs little oxygen and can live without oxygen. However, it should be noted that if the number of rearing is relatively large and the density is relatively high, the lack of oxygen will still be dangerous, so don't raise too much.

Mary fish is also a small fish, but it is resistant to low dissolved oxygen, so it can live without oxygen. This kind of fish has more habitats in the wild, and can live in fresh water as well as in the sea. It is usually fed with algae and organic debris, and has strong pollution resistance.

Betta fish are generally divided into Chinese betta fish and Thai betta fish. Both betta fish survive in places with low oxygen content, not only them, but also fish of the same family have an auxiliary respiratory organ, which can let them breathe oxygen on the water surface, so they are very resistant to hypoxia and need not worry about being suffocated.

Goldfish has a long culture history in China, and can be cultured in ancient times without oxygenation equipment, so there is no problem without oxygenation. The species of this fish are divided into four categories, namely, grass species, culture species, dragon species and egg species, among which grass species are easy to raise, while other species still require oxygen.

Lamp fish refers to the fish of Lamp family, which is not an accurate biological classification, but small ornamental fish with bright colors can be called Lamp fish. Common varieties include lotus lanterns, traffic lights, red-nosed scissors, etc. Because of their small size, they can be fed without oxygen.