How to keep your new crazy fish, Butis butis, with pictures

LA
You get an idea of his size because his coach's fingers are in this pic.

Name: With a name like Butis butis, you’d think this guy could get a job at the U.N. This predatory gudgeon gets the “crazy” in its name because of the way it lurks waiting for prey -- often upside down. We’ve also seen them called crocodile fish, duckbilled sleeper, and bony snouted gudgeon.

Habitat: Crazy fish live in marine, brackish, and freshwater. They live in rivers and mangrove swamps. They like lots of cover to hide within and/or behind. They occasionally swim in open water but prefer to lurk out of sight of potential prey or other predators. They seem to prefer dimmer lighting. And, keep yours covered. They like to jump.

Water: As mentioned, crazy fish live where rivers run into the ocean -- brackish water. I don’t think you need a particular specific gravity in their water. They’re very flexible in their need for salt in their water. In fact, they probably appreciate a change in specific gravity and pH from time to time. Frequent partial water changes also help keep their nitrogenous waste products under control. If you use artificial sea salt instead of plain old NaCl, you bump up your pH to the point that ammonia and nitrite present serious problems. Change that water a lot.

Wood: Wood reduces the light in your tank -- at least the hefty chunks do. Your crazy fish will “glue” up against it (usually upside down) and try to turn the same color as your wood. He strives to blend in. However, he may go to the backside of your wood and disappear forever.

Rocks: We like slate. A piece of slate leaned against your front glass will keep your crazy fish visible probably 25% of the time. He likes the shade and the security the slate provides. If you lean it against the side, he’s very hard to see.

LA
This is why the crocodile fish can eat feeder goldfish.

Fast Swimmers: When chasing food or when startled, your crazy fish can swim surprisingly fast. Unfortunately, when startled, he’s very likely to smack into the end of his tank. You’ll see some wounded lips and eventually you’ll see calluses if you keep pestering him.

Tank Mates: Feel free to house your crazy fish with non-violent fishes too large to swallow. Gouramis and barbs come to mind. Do not mix him with cichlids. Cichlids and crazy fish both get too territorial to get along together.

LA Pix
Crocodiles really pig out on rosy reds. You can see them in their bellies.

Foods: Crazy fish like all manner of small fishes on the menu. They also like worms and shrimps. Supposedly, they also eat flakes and pellets. We’ve just never tried them.

Michelle Gianvecchio, Maryland, March 16, 2008
Dear Aqualand, I am located in Maryland and have been doing a little bit of research about brackish water fish when I came across your crocodile fish. I recognized them as a fish that we sell at the pet store I work at.
Ours are labeled as "Upside down" gobies and we keep them in
freshwater. We feed them flake food and guppies since they are only
about 3 inches. They eat the flake very enthusiastically but absolutely love guppies. They are housed with a few bottom feeders consisting of a 4" albino bichir and a 5" shovelnose catfish among others. Thanks,

A: Thank you for your report. I'm adding your info to my crocodile fish page. Ciao. LA

LA
But as long as these guys act goofy like this, people will call them "crazy fish."

Last Words: If you like “out of the ordinary predators” (and who doesn’t?), you might want to add Mr. Butis butis to your collection.