Fish are not homeotherms. The body temperature of most fish will change with the change of water temperature. Only a very small number of fish have partial or whole body homeotherm ability, such as tuna, mackerel, opah and porbeagle, but their ability to regulate and control body temperature is still slightly inadequate compared with the real homeotherms. So it's also considered poikilothermic.
1. Basic type: The basic type is also called spindle shape. As the name implies, it looks like a spindle. It is the most common body shape of fish. The biggest advantage of this body shape is reflected in swimming, which is not only fast, but also can migrate long distances. Generally, fish with this shape live in the upper layer of the water, such as carp, crucian carp and so on.
2. Flat type: The flat type fish are mainly rays and rays. They look thin and are relatively flat as a whole. They generally live on the bottom of the water. They move slowly and do not swim fast.
3. Lateral flat type: Lateral flat type and flat type are somewhat similar. Their bodies are also very thin, but they look thinner from the top. From the side, they look like a sail. The common ones are pomfret, swallow fish, etc. They generally live in the middle and lower layers of the water body. Although their swimming ability is not very weak, they are not as strong as the basic type. They can rarely migrate long distances.
4, stick type: stick type is also called eel type, listen to the name to know what kind of, common eel, eel and so on belong to this body shape, the body is very long, many love the bottom of the water in the soil burrow.
