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McCosker's flasher wrasse is among the most spectacular display fish in the reef hobby — males perform daily 'flashing' displays where they extend dorsal and anal fins and flash brilliant electric color across their body to attract females or intimidate rival males. Best displayed in groups (1 male, 3-4 females).
Native range: Western Pacific. Wrasses (family Labridae) are one of the most diverse and successful fish families on coral reefs — approximately 600 described species worldwide, of which 40-60 are commonly available in the marine aquarium trade. The McCosker's Flasher Wrasse is part of the Wrasse (Labridae) - Flasher wrasse grouping, characterized by elongated body shape, terminal-phase sex change (most species), and active reef-grazing or pest-control behavior.
Tank size: 55 gallons. Sand substrate is non-negotiable for sand-sleeping wrasse genera (Halichoeres, Macropharyngodon, Anampses) — 2-3 inches of fine pool-filter sand minimum. Rockwork should provide multiple cave entrances and tight crevices the fish can wedge into for sleeping or escape. Lid: tight-fitting, gap-free. Wrasses are the second-most-common jumping casualties in reef tanks after gobies — a single 1cm gap is enough.
Flow: moderate to moderately strong is preferred by most wrasses — they evolved on current-swept reefs. Lighting: standard reef LED works for all wrasses; the fish itself does not require special spectrum.
Carnivore — mysis, brine, copepods. Most wrasses have very high metabolic rates and need 2-3 feedings daily. Skipping feedings during business travel or vacations leads to rapid condition loss — schedule automatic feeders or vendor-trusted tank-sitters for extended absences.
Safe: Most reef-safe community.
Avoid: Other flasher wrasse males (intense aggression); very small fish during male display events.
Not captive bred commercially. Most wrasses are protogynous hermaphrodites — born female, transition to male as they reach social dominance in a group. Tank breeding of wrasses is rare due to the complex behaviors and pelagic egg-laying that resists captive replication.
Jumping (most common); refusal to flash without harem; aggression between males.
Males perform brilliant color displays with extended fins to court females or intimidate rivals. Happens daily in well-conditioned specimens, especially morning and evening.
Yes — flashing requires social context. A solo male in a tank without females rarely displays.
About 3 inches at maturity. Smaller than fairy wrasses.
Yes — peaceful, ignore corals and most inverts.
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