Most Aggressive Fish Ever?

Obviously, cichlids will probably be the majority, but I'm curious since every fish has their own personality. Personally, the most aggressive fish I've kept was a female dwarf gourami. Tried her in all the aquariums I had, and she'd attack every fish. One day, I put her in a tank with a paradise fish, and he kept her at bay for awhile, but she eventually started relentlessly attacking & shredding his fins. She eventually got to the point where she was so stressed, it left her open to disease. It was very sad because she was a beautiful, pure silver color. Anyway, what are the most aggressive fish you guys have kept, and did you manage to calm the aggressor?

 

I once kept a 5-6 inch female angelfish who constantly laid eggs and I promise you she absolutely hated me. She was so mean and evil, every time I walked by the tank, she'd charge and bump into the glass trying to attack me. She hit the glass so hard that I was able to hear little *thumps* every time she did that. She even did that when she didn't have eggs to protect

 

A friend's one inch jewel cichlid (okay, maybe they were asking for it a little) in one week murdered: 13 tetras, 2 guppies, mercilessly attacked two rainbow ciclids. Worst of all, it physically jumped into a neighboring tank and murdered their betta. Now, I have the blighter but I'm rehoming him soon to a friend's 1000L mbuna tank where hopefully he will be kept at bay.

On an odd note, he was friendly with my other rescued fish a Green Spotted Puffer and the two actively share food at the moment. Go figure eh?

 

That's so funny lol no offense to the dead fish... but wow that jewel cichlid sounds like a savage. Funny it gets along with the gsp haha!

 

For me...Black shark. Killed 3 severums, a polypterus and I don't remember what else. A good few hundred dollars worth of fish.

 

I'd say all African cichlids, and for American cichlids mainly Parachromis species and Amphilophus, plus many others. Boisterous and large barbs and tetras aswell. Aggressive, territorial and predatory are all very different things aswell lets not forget. A fish eating a fish is just apart of the life cycle, most fish will eat others if it can fit in their mouth.. A fish nipping, chasing and non stop harassing is far worse imo.