The Blue‑blotch Butterflyfish (*Chaetodon plebeius) is a reef‑associated marine fish with a bright yellow body and a distinctive blue patch above the mid‑flank.
Scientific Name
Chaetodon plebeius
Habitat
Found on coral reefs in the Indo‑Pacific region—from East Africa and Madagascar to Japan and Australia—typically in shallow lagoon and reef slope areas down to about 10‑30 m.
Conservation
Listed as Least Concern (LC) on the IUCN Red List. However, it relies heavily on healthy coral reef ecosystems, so coral loss and habitat degradation pose risks.
Lifespan
Up to about 5–7 years in captivity under good care (wild lifespan may be longer).
Fun Fact
Juveniles may act as cleaner fish. Also specialized coral‑feeding makes captive care difficult for many aquarists.
Diet
Primarily a coral‑eater (polyps of Pocillopora/Acropora) in the wild; juveniles may also act as cleaners removing parasites from other fishes. In aquariums it requires meaty marine foods and is challenging to keep due to dietary specialization.
Average Size
Grows to a maximum of about 15 cm (≈6 inches) total length.
Location / Placement info
Displayed in the Coastal Reef Exhibit, near the Ocean-View Tunnel
FAQ
What is the lifespan of a Blue Blotch Butterflyfish?
They can live for 5–7 years in captivity; longer in the wild.
What do they eat?
They are omnivores, feeding on coral polyps, algae, sponges, and marine foods.
Are they aggressive?
They are peaceful, but may be territorial with similar butterflyfish.
What is the ideal tank size?
A minimum of 75–100 gallons with plenty of swimming and hiding spaces.
Do they need a specific environment?
Yes, they prefer reef-style tanks with live rock, stable salinity, and low stress.
How big do they grow?
They can grow up to 5–6 inches (13–15 cm) in length.
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