Hello guys, I hope you can steer me in the right direction as far as stocking 2 tanks that i have just freed up by selling what i had in them. I have kept fish most of my life and i am now 48 yrs old but i have little to no experience with piranhas. After selling my very "special" arowanas both that were over 11 yrs old since i got them from babies, i want to dedicate both of these tanks to keeping piranhas. The one tank which is 350 gallons (96x36x24) i want to keep a school of pygos in. the other tank which is considerably larger 525 gallons (120x48x24) i would like to put a monster Rhom or a large Manny. The Manny i am convinced will be almost impossible to find. Anyway, my question to you guys is as follows, except for nattereri, which of the pygos species are the fastest growing? I do like cariba and would be very happy if they put growth on quickly with the proper care or is it another pygo i should be looking at? I look forward to your opinions or experiences with these fish. Thanks