3 mg per liter, otherwise the fish will surface because of lack of oxygen, and will die after a long time. Fish live in the water, but it also needs to breathe. When the water enters from the mouth, it will be discharged from the two gills. When it flows through the gills, because the direction of blood flow is opposite to the direction of water flow, it can exchange gas quickly and efficiently, so that it can get oxygen.
without oxygen? 1. Lantern fish: Lantern fish is a small fish native to the Amazon River Basin in South America. It not only has a wide variety of species, but also has different colors. Interestingly, they also have the characteristics of swimming in groups, which is very suitable for raising in grass tanks. Because of its small size, the demand for oxygen is not high, so it can be kept alive without oxygen.
2. Zebrafish: Zebrafish is a common ornamental fish, and because its genes are highly similar to human genes, it is also commonly used as an experimental fish. This kind of fish has strong adaptability to the environment. As a tropical fish, it can also live in a slightly lower temperature environment and consume less oxygen.
3. Thai fighting fish: Thai fighting fish is a kind of fighting fish. It is produced in Southeast Asia. It is an aggressive fish with strong adaptability. In addition, it belongs to the gourami family. This kind of fish has a characteristic, that is, it has a suprabranchial organ, which is an auxiliary respiratory organ, so that it can breathe to the surface of the water in an environment with low dissolved oxygen.
