1. 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.
2. You should feed your fish a variety of food and not just flake foods. Mix it up with fresher foods from their regular diet. Giving them more a varied diet will increase the general health of your fish.
3. You must always treat the water in the aquarium before attempting to place fish. If you fail to treat the water the fish can die from the condition of the water.