The truth is that fishbowls and tiny tanks are not really suitable for any fish. Stores sell them because people buy them, and people buy them because they want something that will sit on their table and look cute. But if you want to keep fish, you owe it to them to research what they actually need, and assemble a tank that takes care of those needs. Make it at least five gallons There are fish that can thrive in a small tank. Not many! But a few, like bettas, can do well here. The catch is that we’re not talking about a vase or a mason jar; fishkeeping experts agree that the minimum size to properly care for a betta is about a five-gallon tank.