Why do angelfish lose their dark strip and turn gray?

Angelfish may lose their dark stripes and turn gray due to stress, poor water quality, or changes in their environment. Stressors such as aggressive tankmates, inadequate space, or illness can trigger a change in coloration as a form of camouflage or response to their condition. Additionally, changes in lighting or diet can also impact their coloration. Maintaining optimal tank conditions and a stable environment can help prevent these changes.