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McCosker's Flasher Wrasse
Wrasse

McCosker's Flasher Wrasse

Paracheilinus mccoskeri

A small, peaceful flasher wrasse whose males erupt into electric blue-and-orange "flashing" displays to court females and rivals. It is haremic — keep one male alone or one male with several females; two males will fight. An accomplished jumper that needs a tightly sealed lid, and it does best in an established tank with a healthy copepod population.

Temperament
Peaceful
Max size
3.1"
Min tank
55 gal
Reef-safe
Reef safe
Diet
Planktivore
Zone
Mid-water, Open water
Keep one male with several females in a large tank.
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Tankmates

How McCosker's Flasher Wrasse gets on with the rest of the reef, checked pair by pair by the same engine as the live pre-flight.

Best kept apart

A real clash — aggression, predation or a same-genus fight.

Maroon ClownfishMaroon Clownfish (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Purple TangPurple Tang (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Midas BlennyThe Midas Blenny harasses McCosker's Flasher Wrasse, a slender mid-water fish it simply out-muscles. Some care sheets still list the blenny as peaceful, which is why this pairing catches people out.Carpenter's Flasher WrasseTwo Paracheilinus flasher wrasses look near-identical to each other when displaying, so two males treat each other as direct rivals. Documented as almost always fighting, often to the death.Antennata LionfishAntennata Lionfish has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Picasso TriggerfishPicasso Triggerfish (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Domino DamselDomino Damsel (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Falco HawkfishFlasher wrasses are explicitly listed as fish the Falco abuses, especially in smaller tanks.Marine BettaMarine Betta has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Dragon WrasseDragon Wrasse has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Volitans LionfishVolitans Lionfish has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Snowflake MoraySnowflake Moray has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Zebra MorayZebra Moray has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Chainlink MorayChainlink Moray has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Golden Dwarf MorayGolden Dwarf Moray has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.Rectangle TriggerfishRectangle Triggerfish (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Clown TriggerfishClown Triggerfish (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Miniata GrouperMiniata Grouper (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Panther GrouperPanther Grouper (aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Six-Line SoapfishSix-Line Soapfish has a big enough mouth to eat the much smaller McCosker's Flasher Wrasse.

Keep an eye on these

Usually fine, but worth watching in a smaller tank.

Sailfin TangSailfin Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Red Coris WrasseRed Coris Wrasse (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Convict TangConvict Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Emperor AngelfishEmperor Angelfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Regal AngelfishRegal Angelfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Achilles TangAchilles Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Naso TangNaso Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Scopas TangScopas Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Queen AngelfishQueen Angelfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Blueface AngelfishBlueface Angelfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Chevron TangChevron Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Mimic TangMimic Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Scott's Fairy WrasseA dominant male fairy wrasse can bully the less assertive flasher wrasse. They belong to different genera but hold the same spot in the tank — out in open water, picking plankton — and that is what they fall out over. Usually fine if they go in together and the tank is large.Rhomboid Fairy WrasseCross-genus fairy-vs-flasher: the fairy wrasse can bully the less-assertive flasher; generally tolerated but watch a lone flasher being outcompeted at feeding.Valentini PufferFlasher wrasses’ extended fin filaments can tempt the Valentini’s fin-nipping, though these fast wrasses usually cope.Crosshatch TriggerfishCrosshatch Triggerfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Niger TriggerfishNiger Triggerfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Threadfin ButterflyfishThreadfin Butterflyfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Majestic AngelfishMajestic Angelfish (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.Blonde Naso TangBlonde Naso Tang (semi-aggressive) is much larger than the peaceful McCosker's Flasher Wrasse and may harass it.