Spotfin Butterflyfish

Geographic Origin and Biotope: Widespread in the Western Atlantic, from North Carolina and the Gulf of Mexico through the Caribbean to Brazil. Juveniles drift north to Massachusetts via the Gulf Stream. Inhabits coral reefs and sandy lagoon fringes down to 30 meters.

Taxonomy and Morphology: Member of the family Chaetodontidae. Features a highly compressed, disc-like white body. Reaches up to 20 cm in length. Equipped with a small mouth and fine teeth suited for picking at tiny invertebrates.

Social Behavior: Diurnal and active, usually found in stable pairs. Peaceful toward tankmates from other families, but shows territorial aggression toward conspecifics or similar-looking butterflyfishes.

Coloration and Sexual Dimorphism: Silvery-white body with bright yellow dorsal, anal, and caudal fins. A vertical black bar runs through the eye, and a distinct black spot (ocellus) sits on the rear dorsal fin. No sexual dimorphism is present.

Aquarium Setup: Requires a large tank of at least 350 liters with abundant live rock arranged to form caves and grazing structures. A secure lid is needed as they may jump if startled.

Diet and Feeding: Carnivore. Feeds on coral polyps, anemones, polychaetes, and small crustaceans. In captivity, feed 2–3 times daily with frozen mysis, brine shrimp, krill, and chopped seafood. Hesitant to accept dry food initially.

Water Quality: Stable marine chemistry is essential. Temperature 22–28°C, pH 8.1–8.4, salinity SG 1.020–1.025, GH 15–25, and KH 8–12. High sensitivity to nitrate accumulation requires good filtration and skimming.

Compatibility and Tankmates: Ideal for Fish-Only With Live Rock (FOWLR) systems. Not reef-safe under any circumstances, as it will actively consume soft and stony corals, sea anemones, and feather dusters.

Aquarium Reproduction: Undocumented in captivity. Broadcast spawners that release pelagic eggs into the water column during pairing behavior.

Risks and Diseases: Starvation can occur if it refuses to feed upon introduction. Highly prone to marine ich (Cryptocaryon) and skin parasites if stressed or kept in suboptimal water conditions.