My 55gal , i have 2 clowns loaches in there now an 1 SAE, but as the SAE gets to 4" they all seem to get nippy an got to go. I do have 3 live plants in there now, an don't have a algae problem, just trying to keep it that way. As for the 20 gal hex, i got growth on the larger rocks, an all else is kept clean. Had an SAE in there but got real nippy at my powder blue gouromis, he'd hide all the time , but is very happy now it's gone, out an about all the time. I check out these sugguestions, THX All