Threadfin Butterflyfish

Threadfin Butterflyfish (Chaetodon auriga) is a semi-aggressive species that is reef-safe with caution, admired for its eye-catching coloration, including a white body with diagonal black lines, a bold black eye band, yellow dorsal and caudal fins, and a distinctive long trailing filament ("thread") extending from the dorsal fin. Males typically display more vivid coloration and may be slightly larger, while females/juveniles are more modestly colored and lack the extended dorsal fin filament when young. They reach about 9 inches in adult size and should be housed in aquariums of at least 125 gallons.

Provide ample live rock for grazing, hiding spots, a sandy substrate, and wide open swimming space, as this species is highly active and requires room to roam. Keep water parameters stable: salinity around 1.020–1.025, temperature between 72–79°F, and pH between 8.1–8.4. A secure lid is essential, as they are prone to jumping, especially when startled.

Diet should consist of a varied mix of frozen mysis shrimp, brine shrimp, finely chopped seafood, high-quality pellets, algae-based foods, and ideally sponge-based preparations, which replicate their natural diet in the wild. While they may nip at coral polyps or invertebrates, individual behavior varies—hence, they are considered reef-safe with caution. With proper care, the Threadfin Butterflyfish adds beauty, movement, and character to large marine aquariums.

International Aquatics Quarantine & Guarantee: All fish are checked by marine vets, given a formalin bath, and held for 14 days in copper-treated systems. We feed Selcon-soaked food with Kanaplex and Metroplex during quarantine. Unless marked, all livestock comes with our 15-Day Guarantee. You will receive a video of your fish eating before shipment. On request, we also send photos/videos after arrival at IA. Some species are import-to-order (3-10 business days). Many common species are already cleared or near the end of QT.

Several species will be import-to-order and may take anywhere from 3-10 business days to secure. Once your fish is secured, you will be notified, and the quarantine process will then begin.