1. When adding particularly aggressive fish to your aquarium, it is a good idea to move around the rocks and such in the aquarium before placing the new fish into the aquarium. Moving the rocks in the aquarium will allow the fish to go back and stake out their own territory.
2. You should take out any carbon filters in the aquarium when you are medicating your fish. The carbon in the filter will remove the medicine from the water, so it is best to remove it all together.
3. You should always take the time to acclimate your fish to the aquarium. Acclimating your fish will get them used to the environment of the aquarium. Adding fish directly can be too much a shock for your fish and can pose health hazards.