Saltwater Fish
Allen's Damselfish

Species Description…

Scientific Name: Pomacentrus alleni
Common Name: Allen's Damselfish
Species Group: Damselfish
Habitat: Reef Safe
Care Level: Beginner
Temperament: Semi-aggressive
Diet Type: Omnivore
Role in Aquarium: Community Fish
Max Fish Length: 3 (inches)
Min Aquarium Size: 20 (gallons)
Native Range: Eastern Indian Ocean, particularly around Indonesia and Sri Lanka
Pomacentrus alleni - Allen's Damselfish

Pomacentrus alleni (Allen's Damselfish)

Overview

  • Native to the Indo-Pacific, often found in coral reefs and shallow lagoons.
  • Distinctively bright metallic blue body with vibrant yellow anal and tail fins.
  • Known for its active, playful behavior and striking appearance.
  • Hardy and suitable for beginner and intermediate marine aquarists.

Feeding

  • Omnivorous diet; naturally feeds on algae, zooplankton, and small marine invertebrates.
  • Easily accepts marine flakes, pellets, mysis shrimp, brine shrimp, and spirulina-based foods.
  • Feeding small amounts multiple times daily promotes optimal health and vibrant coloration.
  • A diverse diet is important for balanced nutrition and overall vitality.

Habitat

  • Ideal for moderately sized aquariums (minimum 30 gallons) with ample swimming space and structured live rock.
  • Stable and mature aquarium conditions essential for long-term success.
  • Provide plenty of hiding spots, coral structures, and live rock formations to mimic natural habitats.
  • Moderate water flow and effective filtration are key to maintaining water quality.

Fish Care

  • Preferred water temperature: 74-80°F (23-27°C).
  • Recommended pH: 8.1-8.4; specific gravity: 1.020-1.025.
  • Hardy species but sensitive to rapid changes; regular water testing and consistent aquarium maintenance necessary.
  • Monitor for common marine diseases and parasites; prompt intervention ensures best outcomes.

Compatibility

  • Semi-aggressive; best kept with similar-sized or slightly larger, robust tank mates.
  • Generally reef-safe; compatible with corals, but may exhibit territorial aggression toward passive or smaller fish.
  • Recommended tank mates include clownfish, dwarf angelfish, tangs, and hardy wrasses.
  • Territorial nature requires careful introduction and adequate space to minimize conflicts.

Aquarium Behavior

  • Very active swimmer, frequently exploring and interacting with aquarium surroundings.
  • Displays territorial behaviors, particularly in smaller or overcrowded aquariums.
  • Often engages interactively with caretakers, particularly during feeding.
  • Clearly defined territories and ample hiding spaces help reduce aggression and stress.