Your rainbow shark is likely turning white due to stress. Stress is the most common reason why a rainbow shark, or any other fish, starts to lose its color.
Certain factors can cause your rainbow shark to be stressed, including:
- Lack of space
- Incorrect diet
- Wrong water temperatures
- Suboptimal chemical levels
- Changes in the water pH
- Various illnesses and parasites
If you notice your rainbow shark turning white, check if it’s showing any other symptoms, such as fatigue or lack of appetite. Also, check the water condition to see if anything is amiss.