Fish's memory is still relatively long, usually up to about 1-3 months. As long as proper training is carried out, memory can even last longer. Of course, the memory of fish is also related to the species. Some of them are smart and have a good memory. For example, zebrafish can remember the smell when they are young. The reason why people think that the memory of fish is very short is mainly misled by some information, but those who have raised fish know that the memory of fish is still very good.

1. Breathing through gills: Terrestrial animals usually breathe through lungs, while fish breathe through gills. It swallows water into its mouth and then exits it through gills. The blood in gill filaments flows in the opposite direction to the water flow, so that gas exchange can be carried out, thus allowing fish to breathe oxygen from water.

2. Life in water: Fish live in water, and a few can go ashore, but they can't live out of water for a long time. In the water, a fish swims by swinging its torso and fins. The caudal fin can not only provide power, but also change the swimming direction. In addition, fins are needed to maintain balance when swimming.

3. Temperature-changing animals: Fish belong to temperature-changing animals, and their temperature will change with the change of external environment, so their own activities will also be affected. When the temperature is high, they are more active and have a strong appetite, while when the temperature is low, they will not eat.