1. It is important to pay attention to the limitations of the fish you place in the aquarium. Do not place fish into aquariums smaller than there recommended range, this can lead to increased aggression and decreased health.
2. When you purchase your aquarium and the equipment for your setup, do not purchase the fish at the same time. You are going to need plenty of time to cycle the water in the aquarium to make it hospitable for the fish in your aquarium.
3. After establishing your aquarium, pick fish that will add well to the current water conditions in your aquarium. Also be sure to check their temperament and other needs to be sure that they will make the transition in your aquarium smoothly.