I actually kept the water level a few inches lower in that tank than I normally would, wondering if that was a possibility. I guess I won't know for sure for a couple more weeks yet.
Nasties in my ponds? Well...I lost an entire tank of my beloved Goodeids once when a couple of blackbirds drowned in it...likely while catching and eating my fish!...and sank to the bottom while I was away for a few days, fouling the water beyond belief. I have lost a number of larger fish, mostly cichlids, to mink who would dive and catch them; that turned into a literal running gun battle.
We won't even go into detail about the stock tank that the bear climbed into, had a nice bath, took a giant crap in and then left...except to say that I was able to save many of those fish thanks to an unpleasant clean-up.
I have wood and chicken wire tops made up in case mink or bird predation becomes an issue again. I don't worry too much about dragonflies, water beetles and their larvae, backswimmers, etc.; I don't doubt that I lose some fry and smaller fish to those bugs, but to me that's part and parcel of keeping the fish outdoors. In fact, my inground pond was originally intended not to have fish in it; I quite enjoyed just sitting next to it and watching all the little creepy crawlies go about their business just under the surface. I only started keeping fish out there in response to the mosquitoes which, unsurprisingly in hindsight, began breeding like gangbusters.
I'm not specifically trying to breed my fish; I just want to keep them in the best conditions I can, to observe them acting as naturally as they are able. That usually includes inciting them to breed...but also includes expecting many of the fry to be eaten by...whatever.
