"I got an aquarium as a Christmas gift and was thinking about putting sunfish, perch, and largemouth bass in it. Can you give me some links to information about these kinds of fish? And what do they eat - can I feed them regular earthworms?"
What a great Christmas gift! Stocking it with native fish will be a lot of fun. "River" tanks and native fish are becoming a very popular hobby these days. So much so that several native fish organizations have developed full featured sites on the Internet. Some of my favorites are:
Desert Fishes Council (DFC)
When it comes to fish from desert areas, this site has the largest index you'll find of native fish. From North America, to Africa, to Australia, it's all listed here.
Native Fish Australia (NFA)
For those of you who live down under (or wish that you did), the site is an excellent resource. Worth visiting no matter where you hail from.
North American Native Fishes Association (NANFA)
Their web site offers a wealth of interesting native fish articles (check under Information Resources), e-mail addresses for local chapters, listings for events, and links to other native fish sites on the net.
It's important to keep in mind that some native fish can be pretty large. Adult largemouth bass, which are part of the sunfish family, range from a couple of pounds up to 20 lbs or higher (ask any fisherman and they will be happy to tell you how big they can get) Needless to say, they can easily outgrow the average home aquarium. They also eat only live fish, which makes them a bit expensive to keep. Expect to spend several hundred dollars a year on live foods for them. Personally I would not recommend keeping a largemouth bass, due to its size and food requirements.
Darters, shiners, sunfish, topminnows, and even yellow perches are smaller and are more suited to aquarium keeping. They can be fed foods such as insects and worms, which can help reduce your feeding expense. Be sure to check to see which fish are legal in your state, as not all native fish may be collected and kept in the home aquarium.
Good luck, and let me know how your tank turns out.