Green Humphead Parrotfish (Bolbometopon muricatum)
The Green Humphead Parrotfish (Bolbometopon muricatum), also known as the Bumphead Parrotfish, is the largest species of parrotfish, reaching impressive sizes and playing a crucial role in coral reef ecosystems. This species is easily recognisable by its large, bulbous forehead and powerful beak-like teeth, used for grazing on coral and algae.
Key Information
• Small fish safe ❌ No (too large and may be aggressive towards smaller species)
• Small invertebrate safe ❌ No (feeds on live coral and algae-covered surfaces)
• Coral safe ❌ No (actively consumes coral, contributing to bioerosion)
• Minimum tank size Not suitable for home aquariums
• Adult size Up to 150 cm (59 inches)
• Diet Herbivorous, feeding on coral polyps and benthic algae
• Be aware of Requires a massive space to swim; significant contributor to reef erosion; not suited for captivity except in large public aquariums
Appearance and Colouration
• Juveniles
Display a mottled greenish or brownish body with white spots. Their colouration helps them blend into reef environments for protection.
• Adults
Develop a solid green to blue-grey body with a pronounced forehead. Their beak-like teeth, fused into a powerful bite, allow them to break apart coral for feeding.
Natural Habitat and Behaviour
The Green Humphead Parrotfish is found in Indo-Pacific coral reefs, ranging from the Red Sea and East Africa to the Great Barrier Reef, Micronesia, and parts of the central Pacific. They inhabit reef slopes, lagoons, and outer reef areas, often at depths of 1 to 30 metres.
• Social Structure
They are often found in small groups or large schools, particularly in areas with abundant coral growth.
• Activity
Diurnal and highly active, spending the day grazing on coral and algae.
• Role in Ecosystem
This species is a major bioeroder, consuming large amounts of coral and excreting fine sand. A single Green Humphead Parrotfish can produce over 100 kg of sand per year, contributing to reef sediment formation.
Tank Requirements and Water Parameters
• Minimum Tank Size Not suitable for private aquariums
• Water Parameters (for public aquariums)
• Temperature 24°C – 28°C (75°F – 82°F)
• pH 8.1 – 8.4
• Specific Gravity 1.023 – 1.025
• Aquascaping
• Requires extensive swimming space and rock structures
• Large open sandy areas needed to mimic natural environments
• Lighting Moderate to high, similar to natural reefs
• Water Movement Moderate to strong, reflecting their native reef zones
Important Note
Green Humphead Parrotfish are not suitable for home aquariums. Their large size, specialised diet, and role in coral reef bioerosion make them best suited for observation in the wild or in large-scale public aquariums.
In the wild, these parrotfish primarily consume coral polyps, benthic algae, and encrusting organisms. Their powerful jaws allow them to break apart coral, extracting nutrition while contributing to reef erosion.
• Captive Diet (Public Aquariums Only)
• Marine algae and vegetable-based foods
• Calcium-rich diet to support beak and skeletal health
• Occasional supplementation with live rock and coral substitutes
Compatibility and Social Structure
• Temperament
• Generally peaceful within their own species but can be dominant towards smaller fish
• Large, slow-moving fish that require a spacious environment
• Tank Mates (For Public Aquariums Only)
• Compatible with other large, non-aggressive reef fish
• Best kept in schools or pairs to replicate natural behaviour
• Avoid aggressive predatory fish
Important Considerations
• Jumping Behaviour Not a concern due to their large size
• Acclimation Only suited for large-scale public aquariums
• Conservation Status Vulnerable to overfishing and habitat destruction, often targeted for food and the live fish trade
Summary
The Green Humphead Parrotfish (Bolbometopon muricatum) is a massive and ecologically significant species that contributes to reef dynamics through coral grazing and sand production. While fascinating, their large size and specialised dietary needs make them unsuitable for home aquariums. Best observed in the wild or in large public aquariums, they remain an essential part of the coral reef ecosystem.