Answer:
Ok this is very creepy but I think u have the same homework as me. The answer is crayfish are omnivores and primary consumers. They eat water plants and tiny water insects such as snails, worms, etc. Fish eat other fish. They are secondary consumers cuz only a herbivore or an ominvore can be a primary consumer. The difference is one is a omnivore and the other is a herbivore. Also one is a primary consumer and the other is a secondary consumer.