Gourami tend towards vegetarianism, preferring algae-based foods but will eat meaty foods. An algae-based flake food, along with freeze-dried bloodworms, tubifex, and brine shrimp will provide these fish with the proper nutrition while young. Once of significant size, they can be fed aquarium plants part or fully cooked fibrous or starchy vegetables, or fresh (or off) fruits. They do develop tastes, such as an aversion to acidic or strongly flavoured foods such as tomatoes or onions, or fresh stone fruit or citrus.
Pacu are commonly sold as 'Vegetarian Piranhas' to home aquarium While they are not aggressive carnivores like the piranha, their crushing jaw system, used primarily for eating seeds and nuts but also would scavenge as well .
from wikipedia