How big do you need a fish tank to have butterfly fish?

The size of the fish tank needed for butterfly fish depends on the species, as they vary in size. Here are some general guidelines:

- Small butterflyfish species like the Pygmy Angelfish (Centropyge argi) or Coral Beauty Angelfish (Centropyge bispinosa) can be kept in smaller tanks of about 50 gallons.

- Medium-sized butterflyfish such as the Raccoon Butterflyfish (Chaetodon lunula) or the Threadfin Butterflyfish (Chaetodon auriga) need a tank of at least 75 gallons.

- For larger butterflyfish like the Emperor Angelfish (Pomacanthus imperator) or the Regal Angelfish (Pygoplites diacanthus), a tank of at least 180 gallons is recommended.

Remember, these are just guidelines, and some butterflyfish may require more space depending on their behavior and activity level.