This post is cross-posted with my personal website’s Blog.
We recently got some new fish in the lab, Butis butis, commonly called the crazy fish or Duckbill Sleeper. This is a fresh water fish, originating from East Africa to Fiji and belongs to the Eliotridae. These fish get to a maximum size of about 15 cm total length, live in brackish mangrove swamps and estuaries, feeding on small fish and crustacean, and is commonly found in the hobby industry.
The question is, are these fish in fact crazy? These fish tend to be unique because they can be seen swimming, floating, and even eating upside down. This behavior has been noted in nature and in aquariums, where they will also be seen pressed up the glass. They tend to be ambush predators and are often found floating among plants, in any position. Having them in the lab, we have begun filming them and have been able to capture their feeding right-side up and upside down. What will be interesting to see is if the kinematics of their feeding differs between the orientations, as well as if one orientation is better than the other at eliciting successful strikes. In the meantime, enjoy the videos of these crazy fish feeding in the two orientations.
Upside down filmed at 1000 frames per second, played back at 10 frames per second.
Right-side up filmed at 1000 frames per second, played back at 10 frames per second.