An Excerpt from Jim Conrad's
Naturalist Newsletter of March 19, 2008
written in the community of 28 de Junio, in the Central Valley,
8 kms east of Pujiltic, Chiapas, MÉXICO
about 800 meters in elevation, ± LAT. 16° 18'N, LONG. -92° 28'W.

Catfish

FRESHWATER MARINE CATFISH?

As if finding crabs breeding in freshwater wasn't enough, last Tuesday Leuccio brought in a dead catfish he'd just found in a canal. That's it he's holding above.

I carry with me the little Golden Guide called Fishes -- the world's fishes in 160 pocket-size pages. What's interesting about Leuccio's catfish is that the closest thing in the little Golden Guide to our canal catfish is one of the Marine Catfishes, maybe genus Galeichthys.

But Marine Catfish live in saltwater, where I used to think all crabs did their breeding...

I wonder if maybe long ago the Central Valley of Chiapas was occupied by a saltwater inland extension of the Pacific Ocean? As the land rose the connection with the sea diminished and the lake water's salt content slowly dropped. Maybe our crab and catfish species slowly evolved tolerance to freshwater, causing a new species to arise. Maybe here at the very foot of the Chiapas highlands where many springs issue water from the highlands above, we have many endemic and endangered species...

Or maybe freshwater crabs and freshwater catfish looking like Marine Catfish are no big deal at all, just that I haven't heard about them. As soon as I get to where I can browse the Internet I'll find out.