Background and recommended species Congratulations, you're going to be a fish parent! While your role may not be as interactive as that of a dog or cat caretaker, there are some important skills-such as tank set-up and maintenance-you'll need to master to ensure a happy, healthy home for your fish.

Cost To get set up, a 20-gallon tank, filters and air pump, stand, light & cover, gravel, plants, fish and food will cost you about $200 to $250. Feeding costs are very low-about $15-$20 annually-but there will be some electricity used to run the light and filtration system.

Coldwater fish Because they're easiest to care for, fish who live in cold water are recommended for first-timers. You will not need a heater in your tank, as you would with tropical fish, but you will need to ensure water quality with a powerful filtration system.

The most popular coldwater species by far are goldfish-and did you know there are more than 100 different breeds? Here are a few types for you to consider: Common goldfish-These sturdy orange-red fish can grow up to eight inches long and live 10 to 20 years, if properly cared for. Comet-This breed is a bit slimmer in the body, and has longer tail fins. Shubunkin-This fish looks like a comet, and also boasts colorful splotches in a variety of hues from blue and brown to black and orange. Fantail-This goldfish has a rounded body and two tail fins. Veiltail-This dramatic-looking goldfish has long, flowing fins. Bubble-eyes-This interesting breed has bulging water sacs under each eye.

Other options for a coldwater tank include the hardy weather loach, a bronze or brown bottom feeder about three to four inches long. When first introduced to the tank, this fish may spend his time hiding, but will come out at all hours once he's settled in.

Buenos Aires and bloodfin tetras can also live in coldwater tanks. If you plan to keep plants in your tank, note that Buenos Aires tetras will probably eat them. Pearl danios and giant danios will also do well in a coldwater tank, but keep in mind that danios are fast swimmers and will need as much room as possible-at least a 20-gallon tank, preferably a 30-gallon.

Housing Tank: Familiar with the image of a single goldfish in a bowl? That's a great example of exactly how fish SHOULDN'T be kept. The ASPCA recommends a 10- or 20-gallon-aquarium for beginners, which is large enough for a nice selection of fish. As a general rule of thumb, you can have one inch of fish per gallon of water. That means, for example, you could have 10 one-inch-fish in a 10-gallon aquarium, or 5 four-inch-fish in a 20-gallon. Remember to take into account the maximum size your fish may reach. The experts at your aquarium store can help you select fish who will get along with each other and can thrive in a coldwater tank.

Location: Set the tank on sturdy table, stand, or counter, in a place that is convenient to a sink or water source. Do not put the tank in direct sunlight-this makes it harder to control the water temperature and may cause excessive algae growth. Deciding on the perfect spot is a big decision-a 20-gallon aquarium filled with water and gravel weighs more than 200 pounds, so you won't be able to move it once it is set up. Décor: Fish may not care if their gravel is color-coordinated, but they'll greatly appreciate a "hiding" place to chill out. You can use a clean, cracked upside-down flowerpot or arrange aquarium rocks into a cave; there's also a variety of tank décor available at the pet supply store. Plastic plants provide great camouflage, too.

Step-by-step setup  You will need to purchase your equipment, set up your tank and get it running for several days to a week, allowing the water to "ripen," before you add fish.

Once you've decided on a location, rinse the gravel with clean water and put it in the tank; you will need 1 pound of gravel per gallon of water. If you plan to add plants, note that too-fine gravel may pack too tightly to allow roots to grow and spread.

Next, set up the filtration system, and add rocks, wood and other tank decorations. Your aquarium will need one or more filters to maintain water quality. Without proper filtration, fish waste can poison the water-and your pets. The most common types of filters are: - Box Filters, which are filled with activated charcoal and a special fiber. Often placed in the corner or an inside wall of the tank, they are only effective for tanks up to about 10 gallons; - Undergravel Filters, which are flat plastic platforms placed on the bottom of the aquarium and covered with gravel. Good for 10- to 20-gallon aquariums with adequate water flow. Waste trapped in gravel nourishes any plants you may have. On the minus side, cleaning requires complete breakdown of the tank; and - Outside Filters, which usually hang on the side of back of the tank. They are highly efficient and easy to clean, but you must make sure you've bought the proper filter for the size of your aquarium; this information is usually printed on the outside of the box.

Next, fill your tank with clean tap water. You can also buy a chemical neutralizer at a pet supply store to add to the water. Most fish do best in water that has a near neutral pH level around 7-neither acidic nor alkaline. Test your water with a kit from the pet supply store. Some fish require water that's more or less acidic, so please ask the aquarium store staff about the particular needs of any fish you plan to add to your tank.

You will also need to provide a light source for your fish. This is best accomplished with a combination aquarium cover/light fixture, which will also limit excessive water evaporation and prevent anything from falling into the tank-or your fish from jumping out. We recommend a fluorescent fixture to provide full-spectrum lighting, show off the colors of your fish and support plant growth. The light should usually be on a schedule of 12 hours on, 12 hours off.

Introducing your fish to their new home

Start your tank with 3 to 4 small- or 1 to 2 medium-sized fish. They'll be in sturdy plastic bags when you buy them. Simply float these bags in the tank for 15 to 30 minutes, so that the temperature of the water in the bag is the same as the temperature of the tank. Carefully open the bags and let your fish swim out on their own. If you want to add more fish and if your tank can support it, add a couple of fish every week until the tank is complete

Diet There are very good commercial fish foods available. Dried flakes provide a balanced diet, and fresh foods such as live brine shrimp, bloodworms and tubifex worms provide variety.

Number one rule when it comes to fish nutrition: DO NOT OVERFEED! Excess food will fall to the bottom of the tank and spoil, reducing the water quality. It is best to feed several small meals daily, just enough so the fish eat everything before it falls to the bottom.

And here's a quick and cheap (actually, free!) snack for your pets: Scrape off any algae growing on the front glass of the tank so your fish are clearly visible, but let it grow on one end or in a corner. Your fish will enjoy nibbling on the bits of algae growing there.

General care and maintenance Daily: In addition to turning on and off lights and feeding, you will need to monitor the water temperature. Coldwater tanks do not require a heater, but you will want to ensure that the temperature remains relatively constant. An inexpensive liquid crystal thermometer that attaches to the outside of tank will work great. FYI, goldfish can thrive at water temperatures between 50 and 78 degrees Fahrenheit.

Weekly: Every week or two, remove several gallons of water from the tank and replace it with clean, pre-aged water. This will help remove chemicals that build up in the aquarium and that are not eliminated by evaporation or filtration. We also recommend that you test the water quality with a kit from the pet supply store weekly, and scrape any algae that have built up.

Monthly: Clean the filter or replace the charcoal and filter pads monthly. And if you have plants, it's time to prune them.

Fish supplies list - 10- or 20-gallon tank - Gravel - Rocks, wood and other tank decorations - Filter - Food - Algae scraper - Net - Water testing kit - Water conditioner - Aquarium cover/light fixture (we recommend fluorescent) - Thermometer - Optional: Plants, stand.