I have a 13" male trimac in a 75 and he does fine. A male midas would be good. An istlanum male is a sure bet, if you can find one. I haven't had good luck with Viejas and Paratheraps species cuz they aren't as personable and damn near impossible to sex. Wet pets need to be personable IMO. All they fish in my signature are single wet pets and are personable, even the grammode.