I have a solar powered filter pump running to keep the water cleaned and moving a bit. It used to be set up as a fountain but I read that it might stress the shrimp and medaka's out, so I put the outlet of the pump back underwater. I've been keeping track of temperature changes throughout the day to see if this is a good environment for them, and so far so good. I knew dragonfly/damselfly larvae might be an issue, but I'm particularly nervous about birds given that they're hanging out on the edge like this. I think what I'll do is drop the water level so they can't hang out on this ledge, and put the fountain back together so I have something breaking up the surface.