fahaka, i have a 2 incher in a tub in my grow out now cause it chases every fish and eats parts of them! they are all larger and include a 6 inch giant snakehead that i thought might eat the puffer but just gets bitten turns round and threatens then swims off!
any piranha esp blacks and mannys... cold blooded hungry killers like the puffer...
gulper catfish if the tankmate is the same size or smaller...
my 14inch wyckii is doing fine with my cichlids atm, only been three weeks but no problems at all...
Still think he would destroy a snakehead ive seen them smashed by dovii, wolf would be a toss up well placed large black piranha bite could stop the wolf in his tracks, definitly think a goliath tigerfish could take a black with no problem though.