When I first tried hippos many yrs ago,I couldnt keep one to save my life(or the fishes) what I have done since then,(and up to date I have had 4)I had of course many hiding places,enticed them to eat by adding brine shrimp,putting algea sheets of differant kinds in alot of differant places in the tank(clips,rocks with rubber bands)the other red algea olga was a good one too.Also someone told me once to add a grounding probe,which I think is key to help keeping them from being stressed and getting ick.I hope the next thing doesnt bring the tang police out. I have kept tangs for awhile in a 55 gal tank,several differant kinds with no issues.Now I wouldnt reccomend doing this on a reg basis,but for a short time with intentions of upgrading is ok.Hope this helped some