It is best to try to clean the tank as often as every two weeks however, don't over clean your tank or you will remove some of the beneficial bacteria. Most people think that removing this bacteria is a good thing, but it's the exact opposite for a saltwater tank. This bacteria is actually essential to maintain a healthy and balanced aquarium. A few varieties of guppies are the Fantail, Flagtail, Spadetail, Deltatail and the Roundtail. The names of all of these different types of guppies focus on the tails because they are so remarkable and unique. The tail itself is usually about one third of the size of the whole fish. It is possible to mix guppies with other varieties of fish. Dogs and cats require regular visits to the veterinarian, vaccinations, flea and tick medications, etc. Last year the purchase of pet toys was a billion dollar industry. We don't have to worry about buying a tug rope or a stuffed friend for our fish. An aquarium is less of a commitment than larger pets, and can still be a welcome addition to the family home. This is usually the same set up and water balance you will use to house other fish as well, so it should not be a major concern when you add your catfish. Catfish are known to be somewhat goofy and comical, but this may depend on the species of catfish you have. Their behavior will vary, but as a whole, the catfish is an entertaining addition to an aquarium. Check with your local pet store when purchasing fish to find out what levels are appropriate. They vary amongst fish species. Filter cleaning is extremely important. Filters collect waste excreted by the fish and left in the tank in the form of excessive fool. The filters will eventually fill with debris and be unable to do their job unless they are cleaned. These foods can be purchased in flake, tablet, or frozen forms. In addition, there are vitamins that can be added to the foods to replace any nutrients that may have been lost in the freezing or drying processes. Just as we humans don't like to eat the same thing every day, neither do fish. Keep a variety of food handy because they will not eat the same food daily.