I used to see people fishing in the LA River and wonder what they thought they might catch - a rusty can? A shred of tire? Maybe some seasonal polywogs?

But George Wolfe, the avid canoeist and naturalist I met last month as he kayaked the L.A. River, spotted several exotic 6-8-inch fish in the high-walled area a few miles south of the Sepulveda Basin and has concluded that they're South American catfish, so maybe the river is more filled with life than I knew.

A fisherman friend of Wolfe's who analyzed his photos believes the fish is a plecostomus catfish "that comes in many sizes, including a species that grows big enough to feed a whole village. The South American rivers of this fish's native habitat can be quite murky, warm and low-oxygen, so that's why it can survive in the L.A. County Flood control channel," writes G. Wing.

Wing hypothesizes that since Wolfe saw a handful of the little critters, a breeding colony must have established itself on our shores, probably from the release of aquarium fish. (I can just picture a 10-year-old boy biking to the Sepulveda Basin and dumping the contents of his fishbowl into the river rather than keep his fishy friends in captivity).

Will Amazonian catfish now join the legion of other non-native species that have adapted to our environment, like the squawking green parrots who roost throughout the Southland and our alligator/cayman/Loch Ness monster friend Reggie?

Since Wolfe is editor of the California satire website LaLa Times, it did occur me that he was pulling my leg, but decided he would have claimed to have seen Amazonian piranhas in the L.A. River, not a friendly little catfish, if he was.

I don't know how much larger these catfish will grow, or if they'll even survive the hunting birds and heavy pollutants in the river water. But it does remind us that rivers, even concrete ones, are the natural habitat of fish, not just rusty cans. And it's exactly the type of thing that Wolfe hopes to catalog during his upcoming full river trip later this month, broadly titled "A Survey of the LA River and its Wildlife"

If anyone has a better idea on what this fish is, or has seen other fish in the river, drop me a line. In the meantime, just knowing that these little guys are out there is whimsy enough for me, one of those offbeat details about this city that makes me happy.