1. Provide plenty of places for your aquarium animals to hide. Studies have actually shown that the more places a fish has to hide, the less likely they are to do so! Hiding spots also provide safe spots of refuge for smaller fish in the aquarium
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. When adding new species to your aquarium, you have to ease them in. Adding too many fish too quickly can cause the ammonia and chemical levels to raise quickly. Adding fish slowly gives your filter time to catch up.