Instructions
Empty the tank and clean the water. The most common cause of popeye is dirty water. Rinse the tank and any plants or rocks with hot water, and scrub the tank until all residue is off the sides.
Refill the tank with tap water. Don't use distilled water in a betta fish tank because that lacks essential minerals. Treat the water with a conditioner to ensure it's at the correct pH level.
Add antibacterial medications to your water. Liquid antibacterial medications can be purchased from a local pet store and are generally very effective in treating popeye.
Make sure the tank water is warm enough. Colder water isn't as healthy for your betta. Use a thermometer to ensure the tank water is between 78 and 82 degrees. If it's cooler than that, purchase a tank heater to warm it up, or move your fish tank to an area that gets natural sunlight.
Feed your fish properly. A betta fish doesn't need a lot of food to thrive. Feeding a fish two times a day and giving them two to three pellets at each feeding is plenty. Overfeeding your fish can make them sick, and it can cause the water to become dirty faster.
How to Prevent and Treat Popeye in Betta Fish
Popeye is when your betta fish suddenly gets a bulging eye. The cause of popeye is generally a bacterial infection. It can be transferred through dirty water, or the water can be too cold to keep the fish healthy. Popeye for the most part isn't fatal. If you wake up one morning and notice that your betta's eye is bigger than normal, begin treating your tank immediately.