don't know if the pic is good enough quality for id.

western mosquitofish/gambusia

see if either of these match what you saw.

http://web1.cnre.vt.edu/efish/families/poeciliidae.html


http://fishbase.org/Summary/speciesSummary.php?ID=3215&AT=western+mosquitofish

Thought it was mosquito fish but didnt realize there was eastern and western. That is an western. none of big ones had spot on side

There are lots of gam species - go to the second link and run gambusia. Probably 10 kinds in TX.

All but the western are found in isolated springs and are threatened species because of habitat loss and competition with the western species along with other species. Doubt any would be found in a pond.

Agree and hope they are not as you might have a problem with Uncle Sam telling you what to do.