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The Blue Damselfish, Pomacentrus alleni, is a small, vibrant marine fish belonging to the family Pomacentridae. It is characterized by its striking electric blue coloration, often with a contrasting yellow or orange caudal fin. This species is a popular choice in the aquarium trade due to its attractive appearance and relatively hardy nature. In its natural habitat, it plays a role in coral reef ecosystems, primarily feeding on zooplankton and benthic algae.
Physical Characteristics
- Body shape
- compressed
- Coloration
- Predominantly electric blue body, often with a bright yellow to orange caudal fin. Some individuals may exhibit a yellowish tint on the posterior dorsal and anal fins. Juveniles may have a more intense blue coloration.
- Scale type
- ctenoid
- Mouth position
- terminal
- Distinctive features
- Vibrant electric blue body coloration, Bright yellow or orange caudal fin, Small, oval-shaped body
- Dorsal fin
- Single dorsal fin with 13 spines and 13-15 soft rays. The spiny portion is continuous with the soft-rayed portion.
- Tail fin
- Forked caudal fin, typically bright yellow to orange.
- Pectoral fin
- Pectoral fins are clear to slightly yellowish.
- Distinctive fins
- Pelvic fins are typically blue, matching the body coloration.
Identification Tips
Coloration
The most distinguishing feature is its brilliant electric blue body and contrasting yellow or orange caudal fin. This combination is quite unique among damselfish in its range.
Size
Adults typically reach a maximum size of about 7-8 cm (2.8-3.1 inches) total length.
Fin Shape
The caudal fin is distinctly forked, and the dorsal fin is continuous.
Habitat
- Water type
- saltwater
- Depth
- Typically found in depths ranging from 1 to 15 meters (3 to 50 feet), occasionally deeper.
- Environment
- Associated with coral reefs, particularly in areas with rubble, rocky outcrops, and branching corals. They often inhabit lagoons and outer reef slopes.
- Geographic range
- Indo-West Pacific, specifically from the eastern Indian Ocean to the western Pacific. Its range includes Indonesia, Papua New Guinea, the Solomon Islands, and parts of Australia (e.g., Great Barrier Reef).
Aquarium Information
- Care level: beginner
- Temperament: semi-aggressive
- Diet: omnivore
- Minimum tank size: 30 gallons
- Temperature: 72-78°F (22-26°C)
- pH level: 8.1-8.4
- Hardness: 8-12 dKH
- Compatibility: Can be kept with other semi-aggressive to aggressive fish of similar size. May be territorial towards conspecifics or other damselfish. Best kept singly or in a very large tank with multiple individuals introduced simultaneously.
- Special requirements: Requires plenty of live rock for hiding and establishing territories. A well-established tank with stable water parameters is crucial. Provide a varied diet including high-quality flake food, pellets, and frozen foods like mysis shrimp and brine shrimp.
Wild Information
- Conservation status: least concern
- Seasonality: Breeding typically occurs year-round in tropical waters, with peaks influenced by lunar cycles and water temperature.
- Market price: Typically low to moderate for aquarium trade specimens.
- Commercial importance: medium
- Taste: Not typically consumed due to small size.
- Texture: Not typically consumed due to small size.
- Nutritional value: Not typically consumed due to small size.
Key Facts
Territorial Naturebehavior
Despite their small size, Blue Damselfish can be quite territorial, especially towards other damselfish or similarly sized fish, particularly in smaller aquarium environments.
Reef Dwellerinteresting
They are integral members of coral reef ecosystems, often found darting among corals and rocks, seeking shelter and food.
Dietary Flexibilitybehavior
As omnivores, their diet in the wild consists of a mix of zooplankton, benthic algae, and small invertebrates, showcasing their adaptability in foraging.
Aquarium Popularityinteresting
Their striking coloration and hardiness make them a very popular choice for beginner and experienced marine aquarists alike.
Safety Information
Handle with care- Safety level: caution
- Venomous: No
- Edibility: not recommended
- Handling notes: While not venomous, damselfish, including Pomacentrus alleni, possess sharp dorsal and anal fin spines that can inflict painful punctures if handled carelessly. Always use caution and avoid direct contact with spines. They can also deliver a small bite if threatened, though it is not medically significant.
Similar Species
Sapphire Damselfish
Pomacentrus pavo
P. pavo generally has a more uniform blue coloration without the distinct yellow/orange caudal fin of P. alleni. P. pavo also tends to have a more rounded caudal fin.
Blue Devil Damselfish
Chrysiptera cyanea
C. cyanea typically has a more intense, darker blue body and often has a black spot at the base of the dorsal fin, which is absent in P. alleni. The caudal fin of C. cyanea is usually blue or clear, not yellow/orange.
Neon Damselfish
Pomacentrus coelestis
P. coelestis is also bright blue but typically has a clear or slightly yellowish caudal fin, lacking the vibrant orange/yellow of P. alleni. P. coelestis also tends to be slightly smaller.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Perciformes
- Family
- Pomacentridae
- Genus
- Pomacentrus
- Species
- alleni
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