“In order to breed fish in a small tank (less than 20 gallon), you need to be an experienced fish keeper. Novice fish keepers need to start with at least a 39 gallon fish tank.”

A lot of people choose to learn through trial and error when learning something new. That might work when caring for aquatic animals but there could be an unexpected price to pay. If you don’t pick the right size tank, it might become a bigger problem than you would think.

“I am going to start with a small tank and then move it to a bigger tank as time goes by.” This kind of thinking is very dangerous. I will go into the reasons why.

Small tanks are harder to take care of.

It might sound weird but many experienced fish keepers will agree.

Compared to a large tank, a small tank contains relatively less amount of water. So due to internal or external factors, there can be a sudden change in temperature or water parameters in the tank. For example, if a room the tank is in gets a lot of sunlight during the day, the room temperature can go from 65 degrees to 78 degrees, and that change in temperature will directly affect the temperature of the water in the tank. If there was a lot of water, i.e. a big tank, this change would occur very slowly, whereas because the small tank contains less water, the change occurs faster. Although most fish can adjust to this change, rapid changes in water parameters can cause stress. In extreme circumstances, their immune system can become compromised and they can catch a disease or even die.

The water temperature is not the only problem. The fish’s excrement or even the leftover food can cause abrupt changes in water parameters. So even though it is a small tank, you would need to perform frequent water changes. On the other hand, big fish tanks contain a lot of water so the water parameters do not change abruptly so you can get away with less frequent water changes making it easier for novice fish keepers. 

Aquatic animals grow and breed

The fish that you can buy at the fish store are usually young. When you buy them and keep them, they grow fast. It is wise to research how big that breed of fish grows before purchasing.

Also, adult fish can breed and pretty soon, baby fish hatch. In this case, small tanks can get overcrowded and the water quality can become hard to control. That is why if you buy a bigger fish tank, you can keep them in the same tank longer.