I stepped into my backyard pond today to repair an air hose and when I got out, I noticed about 50, small (3 mm), transparent, larvae looking critters attached to my feet. Water alone would not wash them off, they were fastened, like a leach. I’ve never noticed them before and do t know if they are good or bad. The pond is about 400 gal with hyacinth, water lilies, kankong, Papyrus, guppies and 2 red-eared, slider. Any ideas? Good, bad? Ph is around 7.4, and N, P, and oxygen levels all good.