Any chance the the HITH could be linked to such high protein, highly carniverous diets? The pellets we feed are high in protein as is the tilapia, shrimp and just about everything else. What if they, like piranhas, need some sort of fruit or algae in their diets? Piranhas are known to eat fruits and nuts as well as fish, so isn't it possible that these fish, some from similar blackwaters, need this too? It may become more prominent as they get bigger because we need to feed them high amounts of food. Maybe they're being over fed? If you've ever seen a WC PB, they usually look very streamline and a lot slimmer than ours seem to look. Maybe the answer isn't to let them eat as much as possible. They are opportunistic predators, so they will eat a lot, as much as we let them. They don't get to eat 15 pellets in the wild for dinner. They eat maybe a couple of fish per day, or maybe sometimes none. I could be completely wrong, but we can't rule it out, can we?