I have raised fish since I was a child, and countless small fish died at my hands. The summarized experience is also very valuable ... only two things are easy to die: one is that water quality, environment and oxygen are not suitable for its survival, and the other is the most important fish quality and survival adaptability. I recommend two kinds of fish. Personally, I think they are beautiful, energetic and tenacious, and they can hardly be raised! And in winter, you don't need any circulation, oxygenation, heating and so on, saving money! 1, Chinese betta is in the tropics. The appearance of male and female is different, and it is bright. It is a small fish, and its adult body length is only 3-4 cm. Suitable for small fish tanks, aggressive and fierce, but the small mouth can only pose a fatal threat to millet and shrimp at best, and it is also one of the favorite live foods. 2, the round body of the moon fish is not easy to distinguish between male and female. There is no obvious feature. A ferocious and bloodthirsty mouth can devour all fish and insects within the diameter of the mouth. As long as it is a small and medium-sized fish, it can grow to more than 30cm a catty at most, but it grows quite slowly. It needs a slightly larger aquarium. Is it one of the most tenacious fish I have ever seen? You don't need oxygenation or circulation. You don't need to change water for a winter, but you need reliable anti-jump measures when you are hungry! These two kinds of fish are native fish, and native fish are super tolerant!