5w Oxygen Pump Maximum can be used in 50 cm fish tank. The bigger the fish tank, the more water it contains. To ensure the overall dissolved oxygen at a higher level, there is a certain requirement for the power of the oxygen pump. Otherwise, if the power is too low, the increase of oxygen can't compare with the consumption, and the fish will still lack oxygen. However, oxygen pump is not necessary. If the number of fish raised is small, or the demand for oxygen is not high, it can be fed without oxygen pump.

1. Goldfish: Goldfish is a common ornamental fish, which is small in size and doesn't need high oxygen, so it can be raised without an air pump. However, it should be noted that the feeding density should not be too high, otherwise the oxygen consumption will be too much, which may also lead to the phenomenon of floating head of fish.

2, guppy: Guppy is a small tropical fish, its length is only about 5 cm, and it has many kinds. No matter which one, it has a beautiful big tail. Under normal circumstances, this kind of fish consumes very low oxygen, so long as the water is changed regularly or a filter pump is installed, sufficient dissolved oxygen can be ensured.

3. Betta: There are many kinds of betta, the most common of which is Thai betta. No matter which species, they don't use oxygen pumps. Because this kind of fish has an auxiliary respiratory organ-suprambranchial organ, which can help fish breathe in the air, even if the oxygen in the water body is very low, they will not lack oxygen.