Chaetodon semilarvatus The Golden Butterflyfish is also known as the Red-lined Butterflyfish. A 50 gallon or larger aquarium with peaceful tank mates provides a good environment. The Golden Butterflyfish can be kept in pairs or small groups in a larger aquarium, but it is best to add them all at once. A diet of vitamin-enriched live foods or fresh clams may be needed in the beginning. Provide herbivore preparations once the fish begins eating.