Here are some possible causes:
* Fin Rot: A bacterial infection that causes the fins to deteriorate and fray.
* Scale Rot: A bacterial infection that affects the scales, causing them to become cloudy or discolored and possibly fall off.
* Parasites: External parasites like ich (white spots) or flukes can cause irritation and damage to the scales and fins.
* Stress: Even being alone, a Betta fish can be stressed by poor water quality, improper tank conditions, or even a sudden change in environment. Stress can weaken their immune system and make them more susceptible to disease.
* Fungal Infections: These can appear as cotton-like growths on the fish's body.
What to do:
1. Isolate the fish: Immediately move your Betta to a clean, separate container with fresh, dechlorinated water. This will prevent the spread of any disease.
2. Observe closely: Note any other symptoms like lethargy, loss of appetite, or changes in behavior.
3. Test water parameters: Make sure the water quality is good. Bettas need temperatures around 78-82 degrees Fahrenheit, a pH of 6.5-7.5, and ammonia, nitrite, and nitrate levels should be at 0 ppm.
4. Seek professional advice: It's highly recommended to consult a veterinarian or a knowledgeable fish expert. They can diagnose the problem and recommend the appropriate treatment, which may include medications, water changes, or adjustments to the tank environment.
Important Note: Never use aquarium salt on Betta fish, as it can be harmful to them.
Taking immediate action is crucial for your Betta's health and well-being. Early intervention can significantly improve their chances of recovery.