Happy Valentine’s Day to the Fish That Builds Walls – For Love.

Hornyhead chub, Fishes of Wisconsin poster. Photo: A. Hinterthuer

Happy Valentine’s Day! Considering we’re still talking about a certain wall two years after we first published this, we thought it was time to reshare the tale of a fish that builds walls – for love!

(originally posted Jan. 27, 2017) — Maybe it’s too soon for jokes about walls but, hey, it’s Fish Fry Day and we’ve got hornyhead chubs on the menu and, well, that name is already pretty darn funny. Heck, even their scientific name sounds like it might be some tongue-in-check taxonomic joke – Nocomis biguttatus. But laugh all you want, because these fish (and, in fact, many species of chub) are extraordinary when it comes to construction. Don’t believe us? Check out this video:

Yep, you are, indeed, watching a fish grab rocks and pile them into a wall. Who needs tiny hands when you’ve got a slightly subterminal mouth perfect for moving pebbles? In the case of chubs, the motivating force behind their wall-building is love or, as it’s known in the world of fishes, reproduction. A male chub builds a mound of gravel in a slightly deeper, fast-moving section of a stream, then aggressively guards his creation from any other males of his species as he waits to catch the eye of a passing female.

But what’s interesting is that this aggression stops at rival males – the mounds chubs construct become crucial spawning structure for other species of fishes in the stream like shiners, dace, stonerollers and more. In a study of Wisconsin’s Allequash Creek, for example, common shiners and rosyface shiners both spawned on hornyhead chub mounds. In fact, while the mound’s architect was busy repairing his structure, common shiners were observed defending the mound from rival hornyheads. Check out another video – this one in a Tennessee stream where shiners are spawning on a mound built by a redtail chub.

In an article in The American Midland Naturalist, Stephen Vives, who was then at UW-Madison, writes that the hornyhead chub can be considered a “keystone” species as the mounds it constructs are crucial to the reproductive success of so many other fish species in the stream. There’s probably a lesson in there somewhere…a fish builds a wall that, in turn, spreads the love and builds community as the fish learns to live with its neighbors…but what do we know? We’re only scientists!

Information for this post courtesy of the USGS, WDNR, and other state and federal agencies tasked with learning about our world and then sharing what they’ve learned with the public that funds them.