I have 2 deppi in a 150 that are only 4" and the male is king of the tank. He rules over severums twice his size and a male HRP that has probably twice the body mass he does. Never kept lyonsi before but I'd imagine they're like most amphilophus and when paired up will be equally aggressive. I don't think I'd risk it. Keep them to a species only set up if you're doing pairs