One-gallon tanks are too small to provide enough swimming space for white cloud mountain minnows. These fish are active swimmers, and they need plenty of room to move around. In a one-gallon tank, they will be cramped and stressed.
One-gallon tanks are also difficult to keep clean. Fish produce waste, and this waste can quickly build up in a small tank. This can lead to water quality problems, which can make the fish sick.
In addition, one-gallon tanks are not stable enough to support a healthy ecosystem. The water temperature and pH can fluctuate easily in a small tank, which can stress the fish.
For these reasons, it is not recommended to keep white cloud mountain minnows in a one-gallon tank. A minimum of a five-gallon tank is recommended for these fish.