They are a type of silverside. If that is what is in the pond you should see them swimming near the surface as they feed. Silversides are normally a topwater type of fish. When predators chase them they will jump 'skip' out of the water avoiding predators. You won't really know for sure what is in the pond until you set a fish trap and catch some. The water quality of the pond does not look good enough for this type of fish to live in the pond. From my reading so far, it appears they thrive in water with pretty good overall water quality, not the stuff in your pictures above.
Limited US Distribution:
http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=317

Picture & drawing. Around 21 species of them in the genus Chirostoma
http://eol.org/pages/16281/overview

Detailed Study:
http://www.scielo.org.ar/scielo.php?pid=S0327-95452006000100018&script=sci_arttext

Diet Study:
http://books.google.com/books?id=40DqktQ...oma&f=false

Last edited by Bill Cody; 11/24/14 05:32 PM.

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