Description

The McCosker’s Flasher Wrasse (Paracheilinus mccoskeri) is a vibrant and active marine fish, prized for its dazzling coloration and dynamic behavior. Native to the Indian Ocean, from East Africa to Thailand and northern Sumatra, this species inhabits outer reef slopes over rubble, algae, or coral at depths ranging from 5 to 50 meters .

🐠 Physical Description
Size: Reaches up to 3.1 inches (8 cm) in length .

Coloration:

Males: Exhibit a vibrant orange-red body with horizontal blue stripes and a yellowish belly. The dorsal fin is orange with red, yellow, and blue accents, featuring a single elongated ray. The anal fin displays a striking red band with blue highlights .

Females: Display more subdued coloration with shorter, rounded fins .

Distinctive Features: Males possess an elongated dorsal fin filament, which they flare during courtship displays .

🧪 Aquarium Care Requirements
Minimum Tank Size: 55 gallons (208 liters) .

Water Parameters:

Temperature: 72–78°F (22–26°C).

pH: 8.1–8.4.

Salinity: 1.020–1.025 SG.

Alkalinity: 8–12 dKH .

Tank Setup:

Provide ample live rock with caves and crevices for hiding.

Ensure a tight-fitting lid, as they are known jumpers .

A soft sand substrate is recommended, as they may burrow or rest near the bottom .

🥗 Diet and Feeding
Natural Diet: Primarily feeds on zooplankton in the wild

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In Captivity:

Offer a varied diet of enriched frozen mysis shrimp, brine shrimp, and finely chopped seafood.

Supplement with high-quality flake or pellet foods.

Feed multiple small meals daily to meet their high metabolic needs
Aquatic Community
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🤝 Behavior and Compatibility
Temperament: Peaceful and social; suitable for community reef tanks.

Reef Safe: Yes; they do not harm corals or invertebrates

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Tankmates: Compatible with other peaceful fish. Avoid housing with aggressive species that may outcompete them for food or nip at their fins

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Social Structure: Best kept singly or in harems with one male and multiple females. Males may display aggression towards other males of the same species

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⚠️ Special Considerations
Acclimation: Sensitive to changes in water parameters; use a drip acclimation method to minimize stress
Aquatic Community
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Jumping Behavior: Known to be jumpers; ensure the aquarium has a secure lid to prevent escapes
Bulk Reef Supply
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Sleeping Habits: At night, they may form a mucus cocoon or wedge themselves into rock crevices for protection
Reef App
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📝 Summary
Attribute Details
Scientific Name Paracheilinus mccoskeri
Common Names McCosker’s Flasher Wrasse
Size Up to 3.1 inches (8 cm)
Temperament Peaceful
Diet Carnivorous (zooplankton feeder)
Reef Safe Yes
Minimum Tank Size 55 gallons (208 liters)
Care Level Moderate

The McCosker’s Flasher Wrasse is a stunning and active addition to reef aquariums, offering both visual appeal and engaging behavior. With proper care and a suitable environment, they can thrive and become a centerpiece in your marine setup.