Freshwater aquariums are by far the most popular way to keep ornamental fish. A medium-sized aquarium holds 10 to 30 gallons of water and is recommended as a good starting point for new hobbyists. These tanks are cheap and easy to handle. A brand-new 20-gallon complete setup usually runs between $100 and $150. For the most part, "bargain" 10-gallon packages usually aren't bargains, since the components are rarely high quality.
Once you buy the tank, you need to decide where to put it. Keep in mind that a gallon of water weighs about 8 pounds, so a 20-gallon aquarium with filter, hood, rocks, gravel, plants and fish can weigh close to a backbreaking 200 pounds.
The Power Filter
Selecting a filter is serious business. In most cases, an undergravel biological filter or an out-of-tank power filter is adequate. Since you can never have too much filtration, though, you might want to combine the two.
If you have an undergravel filter, you'll either need an air pump or something called a power head, which pulls water through the filter.
Let There Be Light
Lighting – which simulates daylight – is super-important for a healthy aquarium, and it's often neglected. Fluorescent lamps, built into the tank hood, are usually best. Hoods are easy to install and keep fish from jumping out. They also make it easy for you to reach in and out of the tank for maintenance and feeding.
Avoid incandescent lights because they give off heat, which can stress out your fish.
Keeping Your Fish Warm
Just like you, your fish needs to be warm and comfortable, so a heater is an essential part of a good tropical or subtropical aquarium. Most come with a built-in thermostat to take the guess work out of keeping temperatures steady. Most freshwater tropical fish like their water between 75 and 78 degrees Fahrenheit. On the other hand, saltwater tropical species prefer the water a little bit warmer, usually 78 to 82 F.
Goldfish and koi don't need heaters and thrive at temperatures around 60 F. However, they can deal with a range of temperatures and can be kept outdoors year-round in temperate climates.
Aquarium heaters vary widely in terms of power so make sure you choose the right one for your tank. A good rule of thumb is 4 watts of heater per gallon of water.
Crystal Clear Water
You don't need a degree in chemistry to understand how to keep your water clean, but there are things you need to think about. These include ammonia, hardness, nitrate, oxygen, pH, salinity and temperature.
If you use a good filter and don't overload your aquarium, you've won half the battle. Since poor tank water is the major cause of aquarium problems, changing it monthly can keep your fish from getting sick or worse. Use a water quality test kit and change the equivalent of 1 percent of the aquarium's water per day.
A great aquarium is more than a collection of heaters, filters and lights. Your fish need more than just clean water and food; almost all of them have a better life if some ornaments are added to their aquariums.
Here are some tips on selecting aquarium accessories. However, with thousands of different types of pet fish, it would be impossible to list every specific tank need.
All items placed in an aquarium must be safe for your fish. Avoid things that can carry diseases, such as rocks or driftwood from a natural body of water (ocean, lake, pond or stream); things that may give off a toxin, like garden or field stones exposed to fertilizers or pesticides; and objects that are sharp or that can trap your fish.
Hideouts Are Important
Items that can provide security, breeding habitat and a resting place for your pet include plastic plants, PVC tubes, aquarium-safe driftwood and specially designed ceramic ornaments. Some fish have rather specific needs. Here are some examples: