Fish that are described to have a very special diet will have a carnivorous diet. For example, a guppy can prefer carnivores instead of the usual fish food and will completely ignore any fish food in the tank. Fish with this attribute will prefer guppies, carnivores, or ultravores instead of their usual fare. Rocky - Rocky is a small guppy and voracious eater that eats ultravores despite being disproportionately smaller than them.