Fish are a great pet to have in the house; they are easy enough to take care of that a young child can be put in charge of the tank, and they are undeniably relaxing to watch. Taking care of aquarium fish is easy; there are just a few things to think about.
First, do not be tempted to overcrowd the fish tank. The water will become dirty very quickly leading to high fish mortality. A rough guide is to provide one gallon of water for each inch of aquarium fish. So a one-gallon tank should, at most, hold two one-inch fish or one two-inch fish. It is always better to under fill than to overfill, so start small.
Very small aquariums can be kept clean without having to plug in a filter or an aerator. But you must still do some things to keep the aquarium fish clean and breathing. For cleanliness, there are naturally occurring bacteria that will help turn fish waste into inert chemicals; however you still have to change the tank water. Plan to change at least half of the water every month. Just scoop out one gallon of dirty water and replace it with clean, chemical-free water.
Aquarium fish will also benefit from a little green plant growing in their home. Pet stores generally have a variety of water plants for just a dollar or two. Pick something that floats free in the water or a little plant to anchor in the gravel at the bottom of the tank. The bright green leaves make the tank look much more relaxing and provide oxygen for the fish.
Larger tanks with more aquarium fish will require a little mechanical help. Filters screen the water in the tank for particles and the whole tank is generally filtered several times a day. As long as the equipment is in good condition, this helps keep the water clean. But still plan on changing about half the water in the tank every month.
Aerators put oxygen in the water for the fish to breathe. An aerator may just make bubbles. There are also aerators that are a sort of arm that vibrates very quickly just at the surface of the water, getting oxygen to the fish but also creating a low sort of mist just above the tank.
Every few months, any tank will require a little extra cleaning. For a small fish bowl, empty the fish into a small holding container and wash out the whole bowl to clean up algae and fish waste. Bigger tanks are too cumbersome to hand-wash; you will probably eventually need an aquarium vacuum.