im not sure but maybe this could help the dreaded 10-12 inch payara death mark.. i had my payara in with a minnows every since i got him at 3 inches.. u could tell when he ate because he had a big bulge in his narrow stomach.. i grew him up to around 71/2 inches to 8 and threw him in the bigger tank .. i have not seen this bulge in his stomach for a couple months now cause he is big enough not to notice it... i got a bunch of those tetras with the big fat bottoms under there mouths for free.(dont know the name} i threw them in the tank with all the minnows and sure enough he smacked down the tetra..and his stomach is huge.. im going to see if he eats all the tetras and leaves the minnows alone..If thats the case i will have one expensive eating fish but will be well worth it if it pays off.