Tropical fish have a special organ inside them called the swim bladder. This is just like a balloon. When the fish breathes in, it can add some air to the balloon. Water is heavier than air, which is why anything filled with air floats.

Choose the largest tank you can afford and can fit in your home. Glass tanks are better than acrylic tanks because they are less likely to break. Tropical fish like warm water but need plenty of oxygen. The warmer the water, the less oxygen there is. Long aquariums allow more air to be absorbed into the water- helping the fish to breathe. Normal furniture is not usually strong enough to support a full aquarium. Ideally, you should buy a purpose-made aquarium stand for your tank.

Aquariums get very heavy when they are full. A 30-UK-gallon tank will weigh about 250 pounds when they are full. Do noplace the tank in direct sunlight or next to a rdiator. The water can become too hot for the fish and encourges the growth of algae.

Fish have an excellent hearing. It is best not to put the tank close to a TV or hi-fi. All aquariums should have a cover. This is known as the hood. A hood prevents unwanted things from getting inside the tank, and also stops more gymnstic fish from getting out!

While your tank is maturing, you can choose your fish. There are 1,500 to 2,000 species of captive tropical fish from which to choose. Each species of tropical freshwater fish belongs to a particular family of fish. The main families kept by tropical fish keepers re : catfish, cichlids, characiformes, cypriniformes, cyprinodonts, laybrinth fish, angel fish and rainbow fish.

Some fish, such as the Red Devil, can be aggressive. It is best to avoid, by isolate to another compartment, as they can fight and upset all the other fishes.

Flat or stocky fish, such as the Clown Loach, are designed to live on, or close to the bottom. Oscar fish which are more on slow-moving tend to have rounded fins.

When you buy your fish, make sure the store is clean and cares for all its fishes. Any fish which has white spots, frayed, fins or dull skin, is unwell. Do not buy it.