Well the only fish I had get stuck was my brother in laws clown fish that I had in my tank while he was putting in hardwood floors, it got stuck and by the time I found out it was too late. The suction force is pretty strong, I have to other fish in there, damsel and a purple pseaudiochromis and haven't had any problem with them, but I just purchased a dwarf lionfish and don't want the same thing happen to him, I might just turn off the powerhead until I get a guard. I have another powerhead but it has one so I am not worried about that one, I also have a canister filter, and a skimmer that is providing some water movement, but the one without the guard is the strongest current though, please help!!