It's all about personal choice here as they come in many sizes and shapes. When you purchase the tank, a kit often comes with it and includes some of the other things you may need. Just to make sure, check that you have a filter and an air pump. These are the most important pieces to the whole set up. The next item on the list of raising a healthy fish is keep the water properly regulated. It is imperative to keep the salinity levels, P.H. and temperature consistent in a saltwater aquarium. Test the water daily and make any necessary adjustments immediately. Check the water for cloudiness and clean the filter regularly. Try to add water that is of the same temperature as the original water in the tank. Add your finishing touches with decorative pieces, then carefully move the fish back in. It may take a little while for the fish to adjust to the new water, but after having followed all these steps, you can be sure that your tank is clean and healthy. A mandarin fish or a dwarf angel fish might round out the collection nicely, and they are fairly compatible clown fish. Whenever adding new fish, choose the species carefully for compatibility. The fish should be compatible with water specifics, but also make sure that their food source is compatible. This should be especially regarded when there are baby guppies in the tank, because guppies will eat their young. The next most important feature to caring for any fish is appropriate water regulation. The specific temperatures are listed above, but it is also important to make frequent water changes. They also possess a strong, hollow ray on their fins that a stinging protein can be emitted from if the fish is irritated or in danger. The most common catfish found in aquariums are the armored catfish. This group is smaller in size than other types of catfish and make a great addition to an aquarium.