I had a Volitans and a Humu together in my tank. They were put in at the same time when the lion was around 3 inches and the humu about an inch and a half. Everything was great for about a year and a half. The lion grew to about 8-9 inches and the humu was around 3 inches. Then one day the humu snapped and tore apart the lion. It chewed off its tail, pecotral fins and most of the dorsal spines. Sadly, I the lion didnt make it, so I would say NO, they dont work out well together. Everythign may be fine for a while but at some point the humu will decide "Hey, I can take this guy"