1. Pay close attention to your fish's PH needs and augment your aquarium as necessary to accommodate the new fish you are adding to your aquarium.
2. You should always stay up to date on the new and exciting practices for fish keeping. Subscribe to several news letters to keep up to date. If you like to read, go to your local library and get some books on fish keeping.
3. It is generally a good practice to purchase the largest aquarium that you can actually afford. A larger aquarium will be less susceptible to quick changes in the chemistry, and will offer much more stability.