As with any living thing, it is best to understand the creature and how to care for it properly before bringing it home. Coral is no different as it is a live animal that you will be adding to your tank. The care and maintenance of coral should be well understood before making the final decision to add this beautiful animal to your aquarium. Water should be kept regulated and tested weekly. Any discrepancies in P.H. and water temperature should be corrected immediacy in order to minimize stress caused to the fish. Stress is significant because it causes illness in fish. It is important to monitor the activity and overall well being of the fish in an aquarium. Choose a bright color to add some interest to the aquarium. In addition, you will need to purchase a filter for the tank. Filters can be complicated. Do a lot a research to find out what type of filter is suggested for the fish that you choose. There are filters that go beneath the substrate in the bottom of the tank, as well as filters that attach to the side of the aquarium. Catfish feel more secure when they are hidden from the light, so be sure to have caves and hiding places for this type of fish. Overall, the care of catfish does not vary from caring for your other fish. You should try to include a food that will settle on the bottom of the tank as these fish are bottom feeders. This is probably the easiest to care for of the five types, simply because you are only dealing with one type of species. Amongst the saltwater fish there are both tropical and coldwater types. They can't be kept together for obvious reasons. The water temperatures vary greatly. Tropical fish are usually brighter in color, and therefore more appealing to aquarium lovers than the fish available in the cold water variety. It also makes the aquarium much easier to maintain in the long run. Keep in mind that only certain coldwater fish can survive in a tank without heat. Most common are goldfish and guppies, but there are a multitude available and you will be able to have an array of fish living in your coldwater tank. The supplies you will need to set up your aquarium may seem lengthy, but it is actually a much shorter and cheaper list than that of a heated freshwater tank or a saltwater tank.