Here is a list of the most common betta fish diseases, the symptoms of these diseases and ways they can be treated properly. Bacterial Infection. The common symptoms of a bacterial infection will be clamped fins and your fish lying at the bottom or surface of the water without moving. These levels should be kept within a healthy range for betta fish to prevent infections and diseases. Avoid overfeeding your betta fish. Overfeeding can cause uneaten food to decompose, which can lead to cloudy eye and other health problems. Feed your betta fish small amounts 2-3 times a day, and remove any uneaten food after a few minutes. If a betta has contracted popeye, other aquarium inhabitants may make the situation worse. Popeye is usually a bacterial infection. We also recommend reading our page on bacterial infections. If caught in its early phases, betta Popeye is easy to cure and your betta should be back to normal after some basic treatment. IiwSS.