Why would you punish a fish for not complying to your wishes. It is a parachromis & they are piscavors(meaning fish eaters) so it is only natural for them to attack other fish. How big is it though for the jardini not to give it a fight you would have noticed a fight. I'd say loiselli but none I've kept were that aggressive.If you really don't want it then take it back to the store you purchased it from. the agression is probaly why it was a give away fish in the first place.
Dude, it was a joke. I know the Jardini has been pickin on him here and there The loiselli is bout 6" id say.... he seems very interactive with me tho. Still going to keep an eye on them for a bit cause I know what my Jar is capable of. Really surprised tho cause he really did sum damage to my Jar..... and I have seen my Jar rip thru fish 3 times it size