NANFA-- Strange Bullhead Behavior - An explanation?

Denkhaus, Robert (
Wed, 10 Jul 2002 10:08:29 -0500

-Tried sending this yesterday but it didn't seem to go through...

Today, I had some leftover bait shop shiners ("crappie minnows") from a
fishing program. As I usually do, I added these to the Nature Center's 100
gallon community tank for the enjoyment of the resident warmouth, longears, et
al. Normally, this results in a typical little feeding frenzy but today, two
3-4 inch long black bullheads each grabbed a shiner that looked to be probably
maximum size for swallowing. Immediately after engulfing the shiners, both
the bullheads began writhing uncontrollably, swimming irratically, spinning,
diving, and virtually every other action that could be described as
uncontrolled movement. Pardon the anthropormorphism but they actually
"looked" like they didn't know what was going on. The odd behavior lasted
about 30 seconds for each bullhead and the bullhead immediately resumed normal
bullhead behaviors after the writhing stopped. Consensus among those in
attendance (all naturalists enjoy watching a good feeding frenzy), was that
the shiners were still alive and through their gyrations inside the bullheads'
deigestive tracts were causing the unusual external behavior. Has anyone else
seen something like this or does anyone have another, better explanation?

Rob Denkhaus
Fort Worth Nature Center & Refuge
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