Rice paddy ditch. A few weeks ago I saw many schools of them in an adjacent ditch which supplies ag water to flood rice fields and feed this pond. I immediately told the owner about this threat and to screen the inlet from that ditch. However this pond sat empty for almost a season before I got consulted. Horse already out of the barn. Catch and cull, keep numbers down, all we can do now. What a bummer. Two things the rice paddy ditches normally have boatloads of, crawdads and bullheads, two species that can survive heat and very low O2.