What do yabbies eat?

Yabbies are omnivores (meaning they eat both vegetation and meat). There are many folk tales about yabbies being either carnivores (from the yabby catchers) or vegetarians (from the aquarium keepers). The truth is they'll eat both. They'll eat bark, mud, slime, insects, each other (yes they can be cannibalistic at times). They are scavengers, thus they'll eat whatever they can get almost. The reason meat is used for catching is because it tends to attract the yabbies far easier. For the same reason (meat being a greater pollutant) in an aquarium, they are usually fed almost entirely a vegetarian diet as it helps preserve the water quality.