Check the fish for injuries when possible. It doesn't need to be a conscious check every day...just keep eyes peeled for the following:
- Ick - tiny white dots that appear on fish body and then proceed to cover eyes and gills after a couple days until fish suffocates.
- Torn or bitten fins
- Bruising or discoloration on fish bodies
- Abnormal fish behavior including swimming sideways or rubbing against rocks or tank walls