Possibilities are cory cat cat, ghost shrimp, or mystery snails which I have been hand removing every week. I assume they are all mystery snails but they seem keep showing up. I know the clutches are above water but could young ones mate and not go up? I see them crawling on each other so I wondered. It is possible a pond snail has gotten in through the plants but I see no difference other than some have not developed color yet and appear like a pond snail I guess, blueish View attachment 1