Fish's memory is not only 7 seconds. Different fish memory situation is not the same, but basically around 1-3 months, and some even longer. Scientists have done such experiments, when feeding fish to turn on the speaker to play music, after a period of training, the fish will hear the music to eat. The fish will be trained to return to the natural waters, waiting for 4-5 months later, and then released the same music, the fish will find the sound to eat.
1. Living in the water: Almost all fish live in the water. Although some fish can be out of the water for a period of time, it is usually not too long. Some fish are particularly vigorous, leaving the water will enter a dormant state, re-entry will recover, but this situation is very rare.
2. Breathing with gills: Fish basically breathe with gills. There are gill filaments in their gills, which are densely covered with blood vessels. When the water flows through, gas exchange can be completed. But there are also some fish besides gills, there are some auxiliary respiratory organs, such as eel can breathe with skin, loach can breathe with intestine, catfish can breathe with gills and so on.
3. Fins and scales: Because fish live in the water, their body shape is different from that of land creatures. They have no limbs, but they have fins, which can make them swim better. And most fish also have scales, a unique skin derivative that can provide some protection.
