Fish that can survive without oxygen pumps are often referred to as "low-oxygen tolerant fish" or "anoxia-tolerant fish".

These species have evolved unique adaptations that allow them to survive in water with low oxygen levels, which is an important trait for fish that live in stagnant or shallow waters.

One of the most well-known low-oxygen tolerant fish is the goldfish. Goldfish are a type of carp that have been bred for their bright colors and unique body shapes, but they also have a remarkable ability to survive in low-oxygen environments. Goldfish are able to survive in oxygen-poor water because they can extract oxygen from the air at the surface of the water using a special organ called the "labyrinth organ". This organ is similar to a lung in mammals, and allows the goldfish to breathe air when the oxygen levels in the water are too low.

Another type of low-oxygen tolerant fish is the African lungfish. This fish is able to survive in both water and on land, and is known for its ability to breathe air when necessary. When the water in which they live becomes stagnant and oxygen-poor, African lungfish will use their powerful pectoral fins to move across the land to find a new source of water. Once they find a new body of water, they will use their lungs to breathe air until the water's oxygen levels are restored.

The walking catfish is another example of a fish that is able to survive without oxygen pumps. This fish is native to Southeast Asia and is known for its ability to walk across land using its pectoral fins. When the water in which they live becomes oxygen-poor, the walking catfish will use its labyrinth organ to extract oxygen from the air. In addition, this fish is able to survive for extended periods of time without food, allowing it to survive in environments with limited resources.

The mudskipper is another fish that is able to survive without oxygen pumps. This fish is able to breathe air using specialized structures in its gills, which allows it to survive in oxygen-poor water. In addition, the mudskipper is able to walk on land using its fins, allowing it to access new sources of water when necessary.

Overall, low-oxygen tolerant fish are an important group of aquatic animals that have adapted to survive in environments with limited resources. These species have evolved unique adaptations that allow them to breathe air, walk on land, and survive for extended periods of time without food. While these adaptations may seem unusual, they are essential for the survival of these species in their natural habitats.

There are several reasons why low-oxygen tolerant fish are important to study. First, these species can provide valuable insights into the physiological adaptations that are necessary for life in oxygen-poor environments. Understanding how these fish are able to survive without oxygen pumps could lead to new strategies for improving the survival of other aquatic animals in similar environments.

In addition, low-oxygen tolerant fish can also provide important information about the effects of climate change on aquatic ecosystems. As global temperatures continue to rise, many aquatic environments are becoming more stagnant and oxygen-poor, which can have negative effects on the survival of fish and other aquatic animals. By studying low-oxygen tolerant fish, scientists can better understand how these animals are adapting to changing environmental conditions and develop strategies for protecting other species in similar habitats.

Low-oxygen-tolerant fish are an important group of aquatic animals that have evolved unique adaptations to survive in environments with limited resources. These species provide valuable insights into the physiological adaptations necessary for life in oxygen-poor environments, and can also provide important information about the effects of climate change on aquatic ecosystems. While these fish may seem unusual, they are essential for the survival of aquatic ecosystems around the world.