Hi I'm new I've just given up saltwater to start a cold water tank with a couple of round gobies. I've found a port near my house which is loaded with them and common shiner( surprisingly the gobies don't seem to be doing much damage) they are invasive to my area but I'm allowed to keep them in an in inclosed water body with absolutely no way of getting to another waterway. I would appreciate some info on how to keep them alive.