....but, if you're going to do it anyway, be sure to completely rearrange the décor in the tank right before adding the GT. Otherwise, the O's will most likely go into territorial mode and attack the new trespasser.
I have three crassipinnis with a pair of green terror .
No problems at all.
My oscars are pretty mean.
They even gave my golden aro a hard time.
The only problem i see is when a pair wants to breed.