My 300 mixed shoal was going great for a long time, i started with 6 piraya , 13 caribe and one red. once in awhile i would find a fish half eaten in the morning , and it was usually a caribe. yesterday i found 1 of my 2 remaining caribe not looking so great by himself, after i got home from work i found his stomach bitten up and an eye missing but he was still swimming. i put him in a spare 60 gallon tank, he was 7 inches and very very wide. that left my 3 piraya and my 1 caribe in the 300. i fed them and hoped my bitten up fish would survive. i awoke to find my bitten up fish floating upside down and the perfectly healthy caribe HALF EATEN. i made sure i fed them that night but they still killed him. i noticed how the piraya keep to themselves and did not include the caribe. what a messed up day.