Description

The term “Bannerfish” commonly refers to several species of fish belonging to the family Chaetodontidae (Butterflyfish) and the family Zanclidae (the single species of Moorish Idol). These fish are popular in the aquarium hobby for their striking appearances, often featuring elongated dorsal fins that resemble banners.

Here’s a breakdown of the most common fish referred to as “Bannerfish”:

1. Heniochus Butterflyfish (Genus Heniochus)

These are perhaps the most frequently referred to as “Bannerfish” due to their prominent, elongated fourth dorsal fin ray. Several species within this genus are popular in aquariums:

• Pennant Coralfish / Black and White Heniochus (Heniochus chrysostomus): This species has a white body with two broad black bands and a long, trailing white dorsal fin. It’s generally considered one of the hardier Heniochus species.
• Longfin Bannerfish / Schooling Bannerfish (Heniochus diphreutes): Similar in appearance to the Black and White Heniochus but typically has a more elongated snout and can be kept in groups more readily. The black bands are often narrower.
• Humphead Bannerfish / Threeband Pennantfish (Heniochus varius): This species has a more rounded body with alternating black and white bands and a less dramatically elongated dorsal fin compared to the others. It develops a nuchal hump as it matures.
• Masked Bannerfish (Heniochus monoceros): This species has a yellowish body with a black mask over its eyes and a long, white dorsal fin. It can be more challenging to keep than some of the other Heniochus.

Characteristics of Heniochus Bannerfish:

• Appearance: Bold black and white or yellow and black patterns are common, often with the signature elongated dorsal fin.
• Temperament: Generally peaceful towards other fish but can be territorial towards their own kind or similar-shaped butterflyfish, especially in smaller tanks.
• Reef Safe: Some species are more prone to nipping at corals and invertebrates than others. Researching the specific species is crucial if keeping them in a reef tank.
• Diet: Omnivorous, requiring a varied diet including high-quality flake or pellet food, as well as frozen and live foods.
• Tank Size: Moderate to large tanks are usually required (at least 180 liters/50 gallons and upwards) depending on the species, as they can grow to a decent size and are active swimmers.

2. Moorish Idol (Zanclus cornutus)

While not a butterflyfish, the Moorish Idol is sometimes referred to as a “Bannerfish” due to its striking black and white (or yellow) bands and its long, filamentous dorsal fin. However, it belongs to its own unique family, Zanclidae.

Characteristics of the Moorish Idol:

• Appearance: Distinctive black and white (or yellow in some regions) vertical bands, a long, tube-like snout, and a dramatically elongated, sickle-shaped dorsal fin.
• Temperament: Generally peaceful but can be sensitive and easily stressed.
• Reef Safe: Can be problematic in reef tanks as they may nip at corals and other invertebrates.
• Diet: Primarily herbivorous in the wild, feeding on algae and sponges. Can be challenging to feed in captivity and often requires a varied diet with a significant vegetable component.
• Tank Size: Requires a large tank (at least 380 liters/100 gallons) due to their potential size and active swimming habits.
• Difficulty: Moorish Idols are often considered one of the more challenging marine fish to keep in captivity due to their specific dietary needs and susceptibility to stress and disease.

In summary, when someone refers to a “Bannerfish,” they are most likely talking about a species from the genus Heniochus (Butterflyfish) with its characteristic long dorsal fin. The Moorish Idol is another striking fish that sometimes falls under this common name.