I checked the TPWD website, and gambusia aren’t even recognized as a fish with bag limits. Idk if that’s a good thing or a bad thing. I will call them tomorrow to see if I’m doing something illegal or not.Gambusia species are native to coastal parts of Texas, but I would still check on state fishing laws. And they are livebearers, so they're not going to lay eggs in the mud.
It is not unusual for Mosquitofish to die en masse when water holes dry up. Their bodies become food for the new life that appears when the water comes again. Removing them could be bad for that particular mudhole.