The Amazon River is renowned for having the greatest diversity of catfish of any river—oh, and it is also the largest river in the world too, I guess. The river drains half of South America and its branches flows through many many different sorts of regions. Near Tena in Ecuador, the river’s tributaries flow through a karst landscape of sunken limestone caves, streams and springs. There, deep beneath the rainforest, scientists have discovered a catfish with a remarkable ability to climb walls—or perhaps I should say they have rediscovered a previously known fish and found out it has unexpected talents.
A team of naturalists led by Geoff Hoese found the catfish in a subterranean waterway jauntily climbing up a sheer 3 meter (10 foot) stone wall with a thin rivulet running down it. Here is a link to a National Geographic article about the catfish—you can go there and watch a video of the catfish shimmying up and down water-slicked rocks. The scientists believe the fish is Chaetostoma microps, a member of the suckermouth armored catfish family (Loricariidae), a group of animals which Ferrebeekeeper has enthused about in past posts (although the fish’s identity remains unclear—since the team had no permit for taking specimens and left the creature unmolested still climbing its underground walls).
Chaetostoma microps is not notably specialized for cave life—it still has pigment and eyes, and lacks the marked asceticism of other true underdwellers like the pink catfish Phreatobius cisternarum (which lives beneath the water table!) Chaetostoma microps feeds on algae—which is notably lacking from underground caves. So what exactly is the fish doing down there? And how/why did it evolve its remarkable ability to climb rocks without much water? The answers are unclear, but it seems reasonable to assume that a fish from the vertiginous yet cave-studded foothills of the Andes would need the ability to climb in order to maximize its habitat (and to prevent being sucked into an inescapable underground grotto). Maybe Chaetostoma microps is really a mountaineer catfish. Instead of leaping like salmon, it deals with its rocky treacherous home by suction, barbels, and indomitable spirit!