I had my overflows uncovered for one night and my flame hawk got in there. I would keep them covered all the time since it can be a PIA to get something out of there.
my Brazilian dragon eel got in my overflow after two days of setting up my eel tank. Was a major pain in the *** getting him out. If you can stick your ahnd in there just pick him up and that would be the easiest way. I ended up having to pull the drain pipe out of the overflow and letting the eel slip down into my sump. Only way I could get him out.
3 eels along with a porcupine puffer, Golden heart trigger,niger trigger,emperor angel, big black spot damsel,and the biggest general starfish you've ever seen.