Fatheads

I bought a "dozen" fathead minnows (Pimephales promelas) and dumped them into the backyard garden pool as an experiment.

http://www.tpwd.state.tx.us/huntwild/wild/species/carpmin/

http://www.fishbase.org/Summary/SpeciesSummary.php?id=4785

http://elib.cs.berkeley.edu/kopec/tr9/html/sp-fathead-minnow.html

http://www.aquarticles.com/articles/ponds/Speirs_Fathead_Minnows.html