Corey Ketchum of the U.S. Fish and Wildlife service holds a giant goldfish found during a survey in Presque Isle, Pennsylvania. The service then posted a warning about releasing petstore goldfish ...

But perhaps its most famous occupant is one that keeps fighting against all odds: the Devils Hole pupfish, a tiny endangered vertebrate that also happens to be the rarest fish on the planet.

Now, we’re begging you to stop releasing pet goldfish into local waterways. The seemingly benign and tiny household pets can grow to gargantuan sizes, like the ones the United States Fish ...