McCosker's Flasher Wrasse

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Common name: McCosker's Flasher Wrasse
Scientific name: Paracheilinus mccoskeri
Max size: 3 in / 7 cm
pH: 8.1-8.4
Salinity: 1.020-1.025
Temperature: 72-78ºF (22-26°C)

McCosker's flasher wrasse is a relatively new fish in our aquariums that quickly have become very popular. This is not surprising as this is a truly stunning species that has the added benefit of being small and that adapts well to aquariums. The only downside of this species is that it is only occasionally available in the trade and can be hard to get a hold of.

McCosker's flasher wrasse is hard to describe without resorting to simply listing superlatives like stunning, beautiful, amazing etc but I will none the less make a try. It has an orange body and the orange color gets darker the higher up on its body you look. Near the belly, the color is almost yellow.  The fish is decorated with several blue lines on its body and on its fins. The anal fin on McCosker's flasher wrasse is red and blue, the front half of the dorsal fin is the same color as the body, and the posterior half is white and red. The eye is red.

McCosker's flasher wrasse is a friendly species that seldom is aggressive towards other species. Males can however sometimes be aggressive towards other micro plankton eaters. It is possible to have several McCosker's flasher wrasses in the same tank, but keeping more than one male should be avoided unless your aquarium is very large. It is best to introduce all McCosker's flasher wrasses at the same time. If that is not possible you should introduce the females before the male. Don't wait too long to introduce the male, because then one of the females might turn into a male. (Read more about this under breeding.)  They can be kept with most other friendly fish species. Do not keep with aggressive fish, large predators or large wrasses.

McCosker's flasher wrasse is considered reef safe and will leave everything but micro invertebrates alone. It is an ideal fish for a small reef aquarium (as well as for large ones).

McCosker's flasher wrasse is not suitable for beginners but is relatively hardy once established. It is suitable for intermediate fish keepers. McCosker's flasher wrasse can be sensitive during the first few weeks in the aquarium. It should only be added to well established aquariums.

Acclimatize McCosker's flasher wrasses slowly and give them at least 4 hours to adapt before releasing them into your new aquarium. They will usually be very shy during the first few days before they start to feel more at home.

McCosker's flasher wrasse originates from the Indo pacific Ocean where they are found from the east coast of Africa to Fiji. Most common in the waters of the Malay Archipelago.

McCosker's Flasher Wrasse care and aquarium setup:

McCosker's flasher wrasse is a small species that can be kept in small aquariums. A 10 gallon / 40 L is enough to house a McCosker's flasher wrasse but I recommend an aquarium of at least 20 gallon / 80 L if you want to keep a harem.

The aquarium should be decorated in such a way that your Carpenter's Flasher Wrasses feel secure and at home in it.  This means a layer of sand on the bottom and plenty of hiding places among live rock. If they are not provided with enough hiding places, your McCosker's flasher wrasses will become very shy and not be the stunning additions to your aquarium that they should be. This specie is very suitable for reef aquariums.

McCosker's flasher wrasse prefers a well lit aquarium with some shaded areas where it can rest. Good circulation and water movement is also important. Keep the water quality high and stable.

The McCosker's flasher wrasse is a very good jumper and it is awfully important to have your aquarium well covered as the fish can jump out of the aquarium through even the smallest opening.

Ideal conditions for McCosker flasher wrasse is pH 8.1-8.4, salinity 1.020-1.025, and temperature 72-78ºF (22-26°C).

Feeding McCosker's Flasher Wrasse

McCosker's flasher wrasse is easy to feed as long as you remember that they need very small food. In the wild they feed on plankton. McCosker's flasher wrasse should be fed a varied diet consisting of very finely chopped sea food and frozen food like daphnia and brine shrimp. It is also advisable to give them prepared food for omnivorous species. Try to include some vegetable matter in their diet. Some, but not all, McCosker's flasher wrasses accept flake food. Feed 3-4 times a day.

Breeding McCosker's Flasher Wrasse

McCosker's flasher wrasse is, like all Paracheilinus species, a protogynous hermaphrodite. Protogynous hermaphrodites are animals where all specimens are born as females and the dominant females develop into males when there is a shortage of males. The dominant female will for instance develop into a male if the male in her group falls prey to a predatory fish. The transformation from female to male can take as little as 10-14 days. McCosker's flasher wrasse lives in harems. Each harem contains one male and a group of females. There can sometimes be subordinate males in a group as well. Sexing McCosker's flasher wrasse is not too hard as males are larger and more colorful.

McCosker's flasher wrasse has, as far as we know, not been bred in home aquariums but occasionally spontaneously spawned in public aquariums. To our best knowledge, no effort has been made to raise fry from these spawnings.

In the wild, McCosker's flasher wrasses scatter their eggs in the pelagic (open water). The actual spawning is preceded by a "dance" where the male follows the female until both fish rapidly swim upward into the water column and simultaneous release egg and milt. The eggs and larvae are carried by the current until the fry becomes free swimming and make their way to the bottom.

This species has as earlier mentioned as far as we know not been bred in home aquariums and if you want to breed McCosker's flasher wrasse in an aquarium you likely need an aquarium large and high enough for them to perform their natural breeding behavior.

Wrasse Articles:

Bird Wrasse – Gomphosus varius
Dragon Wrasse  - Novaculichthys taeniourus
Harliquin Tuskfish – Coerodon fasciatus
Hogfish - Information about Hogfish
Neon Wrasse – Halichoeres melanurus
Ornate Wrasse – Halichoeres ornatissimus
Queen Coris – Coris frerei
Radient Wrasse – Halichoeres iridis
Spanish Hogfish – Bodianus rufus
Striated Wrasse – Pseudocheilinus evanidus
Yellow Coris – Halichoeres chrysus

Line Wrasses:
Fourline Wrasse – Pseudocheilinus tetrataenia
Sixline Wrasse – Pseudocheilinus hexataenia
Eightline Wrasse – Pseudocheilinus octotaenia

Fairy Wrasses:
Exquisite Fairy Wrasse – Cirrhilabrus exquisitus
Lubbock's Fairy Wrasse – Cirrhilabrus lubbocki
Scott's Fairy Wrasse – Cirrhilabrus scottorum
Solar Fairy Wrasse – Cirrhilabrus solorensis

Flasher Wrasses:
Carpenter's Flasher Wrasse – Paracheilinus carpenteri
Dot-and-Dash Flasher Wrasse – Paracheilinus lineopunctatus
Filamented Flasher Wrasse – Paracheilinus filamentosus