Bluestriped Angelfish

Bluestriped Angelfish

The Bluestriped Angelfish (Chaetodontoplus septentrionalis), sometimes called the blue-stripe or bluelined angelfish, is a handsome marine angel from the subtropical Western Pacific. Its brown-to-bronze body is overlaid with wavy electric-blue lines and set off by a bright yellow tail, giving it a refined, scribbled appearance. A member of the same genus as the velvet and scribbled angels, it is a prized, characterful fish for the experienced marine aquarist.

Coming from cooler subtropical waters, it appreciates slightly lower temperatures than most tropical reef fish, and like its relatives it has sponge-based dietary needs that affect its reef compatibility.

Natural Habitat & Origin

Chaetodontoplus septentrionalis is found in the subtropical Western Pacific — around southern Japan, Taiwan, China and Korea — where it lives on rocky and coral reefs, often around caves and rich invertebrate growth, in cooler waters than typical tropical reefs. It is usually seen alone or in pairs, grazing sponges and other sessile invertebrates.

In the aquarium it appreciates a mature system with abundant live rock for grazing and shelter, and steady, slightly cooler temperatures.

Care Requirements

Maintain stable marine conditions: salinity around 1.024–1.026, pH 8.1–8.4, and a temperature toward the cooler end of the reef range, around 22–25°C (72–77°F), reflecting its subtropical origin. Reaching about 22 cm (9 inches), it needs a roomy tank of around 340 litres (about 90 US gallons) or more with plenty of rockwork. A well-established system improves the odds of acclimating it and keeping it well fed.

Diet & Feeding

This angelfish is an omnivore whose natural diet includes sponges, tunicates and algae. As with other sponge-eating angels, replicating that diet is the key challenge: base its feeding on quality marine angelfish preparations containing sponge, supplemented with herbivore foods, spirulina, frozen mysis and enriched blends. Offer small amounts several times a day and allow grazing on mature live rock.

Behavior & Temperament

It is generally peaceful toward unrelated fish but can be territorial with other angels and similar competitors. Keep only one angel of this type per tank unless the system is very large, and introduce it thoughtfully. Newly imported specimens can be shy and benefit from a calm, mature environment.

Tank Mates

Suitable companions are robust, peaceful to semi-aggressive marine fish in different niches — tangs, larger wrasses, anthias and similarly sized community fish that tolerate cooler water. Avoid other angels in smaller systems. In a reef, treat it with caution: like other Chaetodontoplus, it may nip coral polyps, soft corals and clam mantles, so it is safest in fish-only systems or reefs with hardy corals.

Breeding

Chaetodontoplus septentrionalis is a pelagic spawner and is not bred in the home aquarium, so trade specimens are wild-collected.

Common Health Issues

Provided its diet, temperature and space are met, this angelfish is reasonably durable, but it is susceptible to marine ich (Cryptocaryon irritans) and marine velvet (Amyloodinium ocellatum), especially when stressed or freshly imported. The most common pitfall is a specimen that fails to take prepared foods, so choose a feeding fish and offer a sponge-inclusive diet. Quarantine new arrivals and maintain pristine, stable, slightly cooler water for the best results.