I think you have that backwards. My father is crazy about fishing, so I've picked up a little knowledge.
You usually fish for trout in (mountain?) streams. I know a lot of parks advertise their trout streams.
I've actually caught quite a few catfish, and it's always been in ponds and lakes. (I've never heard of catching catfish in a stream.) If you just switch the two, you'll probably be fine.
(Granted, this is all from my experience. I haven't researched it at all.)

Trout was his favorite to fish for. We would fish for, and catch, them anywhere; from creeks a foot or so wide, or the shore of Lake Huron.
The type of trout would vary, of course, depending on whether it was a lake or stream, but if you don’t need to specify type, Trout will work for either lakeshore or stream.

If you do need to specify, in streams we caught mostly brook trout(a.k.a. speckled) and an occasional rainbow trout. We generally didn’t fish for anything other than trout in a stream.

In the spring you could catch smelt and suckers(red horse & black horse).
Smelt only run for a very short time in early spring right after the ice goes out. They are small(avg. 5-8 inches),caught with a net, and only run at night.
Suckers are bottom feeders that run later in spring. I’ve seen suckers so thick you can reach in and grab them. Good eating? Not really, but they’d keep you from starving. LOTS of bones.

From the shoreline, I’ve caught, brown trout, lake trout, perch and bass. I know others who have caught, northern pike, and walleye from the shore, but you usually have to have deeper water for those. A lot depends on the type of shoreline and the depth and temperature of the water.

The memory isn’t as good as it used to be, so I do reserve the right to be wrong.

Edited to correct spelling, again to add information
[This message has been edited by puppysnot (edited April 18, 2007).]

Trout run in cold water streams.

Catfish are at the bottom of lakes and pond near and in the marshy areas. Thier whiskers do sting so I tend to either cut the line and wait until it's dead to retrieve the hook OR take the hook out with plyers. Catfish are really boney, feel like handling rotten meat and if you don't soak the meat for a few hours before you cook them taste funny. They have a fleshy texture more like very tender steak than what you think of for fish.

Also in the lake you can find:

Big mouth bass
Small mouth bass (both kinds are yummy and not too boney. They are best caught by trolling a lure through weedy or marsh parts of the lake)

Northern Pike (nasty things with teeth. If you DO catch one of these you cut the line on drop it into the bottom of the boat rather than risk taking the hook out of its mouth while it's still alive. Real fighters and stay in the deep 10 ft+ water)

Sun fish (very boney but the small ones (about hand sized) stay close to shore and will hit a hook full of worm even in the middle of the day)

Perch (also close to shore)
trout (rainbow)

If you want to shoot me an email (or post it here) about the type of environment you story takes place in, or it's geographic location, I'd be glad to help with making the fish species credible for the environment.

It's kinda a hobby of mine.

Some other notes: catfish whiskers do not sting. On some members of the catfish family, the first spine of the dorsal fin is enlarged and sharp, so you just have to know how to pick them up without impaling yourself. No need to cut the line or kill the fish needlessly.

Pike and related fish can also be safely unhooked, most people use needle-nosed pliers. Again, no need to kill them. The best way to do it is to leave the fish in the water, if it is top be released. Definitely keep your hands clear, though.

Largemouth and smallmouth bass are certainly edible, but there are more desireable species for table fare, if that's of interest.