The difference between koi and goldfish

People who have fish in their backyard water gardens will argue over whether koi -- a species of carp -- or goldfish are hardier and easier to care for. A lot depends on your situation and the habitat you provide. If you want a water garden with fish and plants, keep in mind that koi can knock the plants around, uproot them and even eat them. Goldfish won't disturb the plants, and will enjoy darting around them.

Fish expert Robyn Rhudy raises koi and goldfish and says the major differences between the two are size and cost.

"Because koi grow so much larger, you really need a large pond for koi," Rhudy says. "So you would choose goldfish over koi if you had a pond that was under 1,000 gallons. And then also the cost factor because koi normally cost a lot more than goldfish."

The majority of koi sell for $10 to $50, but exotic fish with elaborate patterns and colors can cost hundreds, even thousands of dollars.

Goldfish are probably better suited to the average water gardener new to the hobby and who doesn't want to spend a lot of time or money. However, choosing goldfish doesn't mean you can't have pretty fish. You might be surprised at the assortment of markings and colors available.

Long-term commitment

Fancy goldfish will have to be brought inside over the winter. Koi will survive cold climates as long as the pond is at least two feet deep.

Whichever fish you choose, plan to have them around for a while.

"Well the average goldfish that doesn't succumb to predators or illness is going to live 10 or 20 years, and the oldest goldfish on record was 43 years old," Rhudy says. "The oldest koi ever was over 200 years old, and an average koi may live 50 years."

When koi get old, they get big, growing to about three-feet long. Goldfish grow according to their environment, and will max out around a foot. If you truly can't decide, it's okay to mix and match. A lot of people have both species swimming around the pond without any problems.