Piraya are my favourite Pygo and I have one I am growing up to check his growth speed. He's done 1" in 6 weeks so far and is getting a fish food vitamin suppliement to aid healthy growth and immune system.
I am just about to get one of these though, so my fav might change this month
Diamond Rhomb's.. but I think RBP's are the most fun.. You don't have to be delicate, or worry about losing one or two.. the price is right, and they can be just as aggressive as any.
ive only owned rbp, like them so much ive never even considered another. am i loyal or ignorant??.................check out the great color, they are just blood red, some times it scares me it looks like a wound.