The absolute most aggressive freshwater fish in the world is the Asian Redtailed Catfish
Hemibagrus wyckioids http
/www.planetcatfish.com/catelog/speci...p?species_id=19 At an adult size of over 3 feet they are the top predator in their range and anything that they see is food, if its too big it will just be dismantled bite by bite and if theyre not hungry they seemingly kill just for fun.
Posts like these make me so proud of my little guy
Some of the users here may know that I once had a 12''
Hemibagrus wyckioids. He was too big for the tank so I sold him for $150 to a guy with an indoor pond. Now I think I could have gotten more for him...

but then I remember that he is probably ecstatic to get a pond to himself.
In the tank with him, I also had a pair of 9'' Oscars that regularly spawned. Unfortunately, whenever they spawned, the catfish would viciously attack the Oscars, tearing scales, ripping fins, and eventually breaking the jaw of the male. He would then consume the eggs. The Oscars were good parents, and they would occasionally threaten the catfish, only to have him seemingly "growl" at the Oscars, sending them into a frenzied dash to the nearest corner.
I eventually resorted to leaving the light on all night long so the catfish wouldn't prowl. If the light got shut off for some reason, I would end up turning it on and seeing petrified, beaten Oscars and a torn-up Plec and Tinfoil Barb.
I will get another one someday. They are incredible cool

I also love snakeheads, but they seem really "jittery" and buying a "jittery" fish makes me nervous...
-Lynden