You can calm angelfish down by:
- Not overcrowding the tank
- Maintaining good tank conditions
- Not disturbing their tank too often
- Providing them with enough food
- Providing them with plenty of plants and decoration to interact with
- Giving them 6 to 8 hours of darkness to rest
- Separating those that are particularly aggressive
- Separating breeding fish as they are prone to stress and aggression
Take action immediately as soon as your angelfish start exhibiting aggression. You’ll notice them fin-nipping, lip-locking, chasing other fish around the tank, or other similarly erratic behaviors.