We tried a couple of times to keep a Plecostomus and a few gold fish in our horse trough to keep the algea and dead insects cleaned up in the trough. The Plecostomus ended up killing several gold fish as evidenced by the sucker marks on their head. I am glad to hear that they don't survive below 50 degrees, my little brother set a Plecostomus loose in our pond many years ago.