[jeb5573]

Have tried this little guy with two Jack Dempsy's and two different Texas Cichlids separately, although not positive if they are (Herichthys cyanoguttatus) or (Herichthys carpintis). Even though this fish is the smallest out of the bunch, and not really "aggresive" in demeanor, the other fish dont seem to like this one around. lt wont actively attack, but constantly following the others and the occasional nip at the tail. All of the combinations of the fish listed have been in a 55 gallon tank. Is the tank size the problem for this combination? The pink one has also shredded the fins up on about a 8" albino pleco. He is currently in a solitary tank.

Also, am assuming this one is a Male?

Second pic is one of the two Texas Cichlids, again am assuming male due to lack of black spot on dorsal fin(not shown in pic)

 

[Auballagh]

Hmmm, well.... I'm guessing that the little Convict has been in the 55 gallon tank the longest of all those fish?
And yes, in the aquarium, New World Cichlids can sometimes turn into some real Pleco-killing maniacs. At least your Pink Convict only went after the fins on that catfish. Some unfortunately - go right for the eyes....
Here is a video that may help to inform about these pugnacious little fish,

*ahem* Sorry, those Andy Woods videos are pretty informal. But, the guy really does know his new World Cichlids.
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You may need to keep your little Convict in isolation for a bit, and allow any larger/meaner/more powerful tankmates to get acclimated to the 55 gallon tank first. Rearrange the interior decor of the tank, and provide one or two good hiding spots that your Convict can safely escape to when the 'big boyz' get tired of his antics.... then put him back him to the tank (preferably at night, after lights out).
Hopefully, that will take care of the 'mean little Convict' problem.
Oh, and no more Pleco catfish should be kept with that little guy.