What is the meanest fish with the worst temperment you have ever kept?

[prcdslnc13]

This guy...

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WANT

 

[columbus shark]

Very cool

 

[UTEP]

Sweet Dovii!

 

[Aasikki]

My "worst" was some kind of Amphilophus... He looked quite like labiatum, but a bit more like hogaboomorum...