Hi Nazasaki, I had a single blood red many years ago in a 55 gallon. She was happy with all types of fish. I kept her with blue gourami, a banded gourami, a jack dempsey, an albino african clawed frog, and a chinese algae eater. It was quite the tank, and it was much more interesting than my amazon themed tank I run today. I would agree that it would probably be best to return the two and keep one especially if you are in anything smaller than a 55 gallon. They have quite the personality, and she ruled the tank believe it or not. I would say that a blood parrot would do well with any larger tetra species as well. Something like a small school of emperor tetras would contrast the red color on the parrot fish very well. My parrot was fairly peaceful, but if something came in her cave, she got mad quickly. Cory's might not be the best choice with a parrotfish for that reason, but I have never tried it. Maybe someone else can chime in who has experience. If I remember I also had a banjo catfish that would annoy the heck out of that parrotfish, so cories might do the same. Good luck.