The Three Kings Islands butterfish, the Orangespine unicornfish, the Bullethead parrotfish, the Bluspine unicornfish and some species of rabbitfish are known to eat seaweed directly. However, many species of fish eat seaweed indirectly when they eat other small sea animals that have eaten seaweed.
Seaweed is also more than simply a meal ticket for many fish, it is a home for them. Some fish like to hide in the small spaces that seaweed offers, like other fish do with coral reefs. Hiding inside of the seaweed crawl spaces gives the fish a better chance of survival when much bigger and stealthier predators swim by looking for food.