short nose gar they are cool looking mean and they are tought they can live in nasty water not that you would want a green tank oh and best part you dont need to go to a pet store for food a lizard/bug/fish/minnoe/craw fish are all on the menu but they stare at you if ur in the room there kind of a odd one but they are aggressive and 100 gal no problem
Tiger and wolf way to big plus you need a monster filter I got a sm peakock and two African jewels and blue gills and 100 gal fluvel filter and two 40 gallon filters and I got green water oh all fish are small 2 inches
If you want aggressive, mean, and deadly, and don't mind only having one fish because it will kill anything else, I would say go with an electric catfish. They have tons of personality and they are beast as hell. Pound for pound as vicious as it get imo