What are the ornamental fish without heating rods?

There are actually many kinds of ornamental fish without heating rods. Except for tropical fish, there is basically no need to heat them, such as koi fish, goldfish and grass goldfish, which are relatively common in China. Generally speaking, as long as the water temperature is around 18 degrees, many tropical fish can survive without heating rods. Such as mini parrot fish, zebra fish, tiger fish, peacock fish, black Mary fish and so on. , can survive in the water temperature of 18 degrees. As for arowana, the best temperature is about 25 degrees. If it is a tropical fish, it is best to keep it above the water temperature 18 degrees. If it is a temperate fish, it is best to raise it at the temperature of water 15 degrees. If the water temperature of tropical fish is too low, it will lead to the decline of activity or even death, while if the water temperature of temperate fish is too high, it will directly lead to its death.