Not only do they need to be compatible for water temperature and P.H., but they also should have similar food requirements. Try to keep the fish relatively the same size. It has been said that if a fish is small enough to fit in another fishes mouth, that is usually where it ends up. So don't be discouraged if this happens. This will cause excess build up of toxic chemicals and can kill your fish quickly. As the water in your fish tank cycles through the nitrogen cycle, you may notice that is becomes very cloudy. This is a normal process and should clear up in a few days. Do not add any new fish until the water is crystal clear again. Aquarium Care Guide- New Tanks When starting a new aquarium it is important to understand the nitrogen cycle. Many new aquarium owners jump into the hobby of fish keeping too quickly. Before purchasing fish, the aquarium must be cycled. This could take anywhere from twenty four hours to four weeks. In an established aquarium there are certain bacteria that help the breakdown of ammonia to nitrates, but they are not present in a new tank because they are generated from existing fish. Be careful not to put prey and predator together in the same tank. Keep in mind that freshwater fish are hardier than the marine variety, and will be less susceptible to water fluctuations. One reason that freshwater fish are hardier than saltwater fish is the saltwater itself. Just like any living creature, a fish's body requires water in order to function properly. Some live plants need to be anchored, while others can be left free floating. Next connect the air pump and filtration system, and fill the tank the rest of the way. Lastly put the lid on the tank and let it cycle for one to two days before adding any fish to the tank. Watch the tank for cloudiness and check the temperature and P. They are just fun to watch. As with any type of aquarium, there are three basic components to caring for the fish. Diet is very important. Guppies should be fed very small amounts as often as three times a day. Guppies will eat just about anything, but their main diet should consist of frozen or flake foods.