If swimming against the flow was a fish-world Olympic event, climbing gigantic waterfalls would be an X-treme sport. 

In tropical island rivers, it’s feast or famine. Yearly rainfall fluctuates between gushing flash floods and desolate patchy pools. You might think such extreme conditions too inhospitable for fish.

Not for the thrill-seeking amphidromous fish! Their adventures start upstream, where adult amphidromous organisms live and reproduce.

On their upriver journey to reproduce, fish often encounter impassable migration barriers, like waterfalls. However, for  amphidromous gobies of the subfamily Sicydiinae, waterfalls are simply a conquerable challenge.

Whereas most fish have a pair of pelvic fins on their underside used for steering and stabilization, gobies (Gobiidae) have a single fused pelvic fin that holds onto rocks, like a suction cup, in turbulent waters. Sicydiinae gobies uniquely use their sucker fins in tandem with their mouths to slowly and methodically climb the faces of massive waterfalls.

Waterfall climbing has its benefits. Not only can these gobies access unoccupied upstream habitats, they can also evade voracious non-climbing predatory amphidromous fish lurking below.

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Written by Patrick Cooney, a certified fisheries scientist who is unable to climb gigantic waterfalls. However, he is a leading expert in sampling and researching waterfall-climbing gobies in Puerto Rico and Hawaii. For his day job, Patrick trains fisheries scientists how to use electricity in water to safely sample fish for scientific purposes, and for fun, he co-founded The Fisheries Blog in 2012 with the purpose of sharing awesomeness about fish.  Patrick is known to media agencies as the guy who spoils the fun of children’s movies by pointing out scientific inaccuracies. Feel free to follow Patrick and his colleagues at The Fisheries Blog on Facebook and Twitter.

Illustrated by Christin Hardy, Buzz Hoot Roar artist in residence.

Check our Facts!

https://thefisheriesblog.files.wordpress.com/2013/05/a568b-amphidromous.jpg

https://docs.google.com/file/d/0BySLY75rM7ZIUjRvczV0SmtTSVU/edit

http://onlinelibrary.wiley.com/doi/10.1046/j.1095-8649.2003.00197.x/abstract

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0053274

https://docs.google.com/file/d/0BySLY75rM7ZIbC1sT1RzZmdwZ1k/edit

http://icb.oxfordjournals.org/content/50/6/1185.short