They are in 1 125g but I have a 7" rhom one other side. I have raise the piraya and the red belly seem they were only 2-4". I had my rhom together with them for over a month but until I got my cariba and tern last week, then I seperated them because the cariba were tried to gang up rest of his fellow to kill the rhom, what a bad as#. below is my rhom with a little missing fin but too serious.
Those Pygos of yours look beautiful and for the Caribe being the most aggressive - I think this happens in most cases, Caribes are totally nuts and thats why I got rid of my Rhom to get a small shoal. Lovely fish. Well done mate!