We have a mbu puffer at about 26" who is in a tank with a learius longibarbis,two giraffe cats,a channa marulioides and two plecs and a fahaka in a tank by himself.The mbus tank is 9ft x 3ft 6 x 2ft which is about right for his size.Mbu puffers tend to be either sociable or savage so its hit and miss but there is substance in the fact of bringing them up with other fish from day one,this gives greater chance of compatability with other fish.I wouldnt try the Fahaka with anything as even if he tolerates them at first I know the clock will be ticking even if they are not piscivores.