McCosker’s Flasher Wrasse: Care | Diet | Size | Breeding Guide

With a name that is a mouthful to get your tongue around, but a look that is certainly easy on the eyes, McCosker’s Flasher Wrasse is a stunning fish for your home aquarium. These orange fish with iridescent blue stripes are surprisingly easy to look after and have a nature that helps them settle in well to established fish tanks.

Everything you need to know about the McCosker’s Flasher Wrasse

Scientific NameParacheilinus mccoskeri
Common NameMcCosker's Flasher Wrasse
Care LevelEasy
Max Size 3-4"
OriginAustralia, Bali, Maldives, Sumatra, Vanuatu, Africa
Tank Size50 Gallons+
Reef SafeYes
Water Conditions72-79° F, dKH 8-12, pH 8.1-8.4, sg 1.020-1.024

With a name that is a mouthful to get your tongue around, but a look that is certainly easy on the eyes, McCosker’s Flasher Wrasse is a stunning fish for your home aquarium. These are surprisingly easy to look after and have a nature that helps them settle in well to established fish tanks.

There is not a lot of information commonly available online about the McCosker’s Flasher Wrasse but if you are looking for something different that will make visitors to your home jealous, we can’t recommend many breeds higher than this little fellow.

What are Flasher Wrasse?

Paracheilinus Wrasse are a species of wrasse which is found in reefs in warm parts of the Indian Ocean and the western Pacific Ocean.

This fish likes to live at a depth of between 5 to 40 m and can be found in happy reef communities in some different and colourful parts of the world, including Africa, Australia, Bali, the Maldives, Sumatra and Vanuatu. This hardy fish likes things warm and bright.

Vibrantly coloured, this is an adaptable and active fish whose male is more colourful and adorned than the female, as is common in brightly coloured fish.

The male has a mostly orange/red body with a yellow belly and blue horizontal stripes. The fish has an orange dorsal fin with striking red, blue and yellow patterns and one elongated ray. They boast an orange anal fin with a bold red band.

The blue stripes and dotted markings along the body and on the dorsal and anal fins are what really sets this fish apart from the school, and are what makes him a bit of a superstar in the home aquarium.

The female of the species is more muted in tone and also doesn’t have the large dorsal and anal fins of the male.

They get the flasher name from a courting ritual during which the male will swim back and forth between his groups of cohorts and a group of females to flash his fins at the females to attract one of them.

During this showing off or flash dance that they do, their colours stand out beautifully and they become the star of the tank.

What does the McCosker’s Flasher Wrasse look like?

The juvenile of the breed is not quite as colourful or flashy as he will grow to become. Before they are fully grown the fish is paler in colour, more of an orange with purple lines running their sides as well as along the dorsal section of the fish. Juveniles also have a white mark above their eye which will disappear as they become adults.

As they mature into adulthood their colours change, with the females becoming a more pinkish colour, while the males turn red. The blues lines on both genders become iridescent and quite striking.

The larger males can grow to be around 10 centimetres long, with the females slightly smaller.

An adult male will have it’s dorsal, caudal and anal fins grow larger and more prominent. The tenth, twelfth and fourteenth spines of the dorsal fin become longer and stick out. He will also develop some blue spots on the dorsal fin.

Females and juveniles are generally quite timid and shy, while the adult males are more confident and may become the life of the party in your tank. The more boisterous and showy male likes to have around 3-5 females that he will mate with.

What sort of Environment does the Flasher Wrasse need?

McCosker’s Flasher Wrasse likes being near the bottom of the tank and will often form small groups with other fish. In the wild, they like the protection and safety of reef slopes and rocks and stones near the bottom. In a tank, they love live rock and a good sandy bottom.

Give them a tank with plenty of light, however, include some shaded areas as well as places to hide.

You need to maintain good quality, clean water and ensure it keeps circulating and moving.

Their ideal water conditions include temperature 22-26 degrees Celsius (72-78 degrees F), pH 8.1-8.4, and salinity at 1.020-1.025.

Although generally placid, they can’t be placed in the tank with all other kinds of fish, and with some other breeds, you may need to use some caution when letting them mix.

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The male can sometimes be aggressive with other micro-plankton eating fish in the tank, and can also sometimes get bullied by more aggressive fish breeds. Don’t put them in with larger or more predatory breeds, or even larger wrasse.

Generally, peaceful and friendly, they do like a large tank, so make sure that they enter a tank of at least 80 and up to 200 litres with plenty of their own space.

They are considered by experts and enthusiasts to be quite reef safe, and will live in harmony with everybody except micro-invertebrates.

McCosker’s Flasher Wrasse tend to jump, so make sure that you have a secure fitting lid to keep them in. They are known as little escape-artists and can jump very accurately through small gaps that they detect. Some experts recommend putting a layer of netting below the tank lid to make sure and keep them contained.

They like to hide behind rocks and other obstacles, and also enjoy burrowing, so be sure to have enough sand in the bottom of the tank for them to do this.

McCosker’s Flasher Wrasse enjoy fresh and live food the most, but will easily switch to frozen and packaged food reportedly. When you find the mix of food that they like they can be quite greedy, so be careful not to overfeed them.

You can keep a single male of this breed on his own, or in a tank with several females, and you can also add them to a community of other breeds. Make sure that you add them to generally placid communal fish as wrasses can get bullied and have their food stolen by more aggressive breeds.

Flasher Wrasse: Tips for Care

Wrasse are a warm salt water fish who like lots of space and some gentle playmates. Males tend to do better as the only male of their breed in the tank and will happily have several female partners.

They are a reef fish and like having live rock to interact with, as well as sand on the bottom of the tank because they enjoy burrowing.

If you are adding males and females to the tank many experts recommend adding the females first, or otherwise add both at the same time. 

This breed of fish will be more comfortable as the only male McCosker’s Flasher Wrasse in the aquarium, although you can have several females. If the male doesn’t have enough personal space he will pale in colour and not flourish.

When you first introduce your new wrasse to the tank he may look quite sad and dull; he is camouflaging himself while he adapts. He should perk up within a day or two and get his natural colours back provided that you have given him all of the requirements he needs in his environment. He may also be quite shy in the beginning but should gain confidence as he acclimatises.

Wrasse tend to make mucous cocoons to sleep in at night, so you may seem them lying still and covered in slime on the bottom of the tank. This is nothing to worry about and is normal content behaviour.

What do Flasher Wrasse eat?

In the wild, this fish likes to eat the zooplankton that swim above the reef.

Beautiful little carnivores, this fish needs protein to thrive and should be fed a high-quality feed such as raw, vitamin-enriched mysis shrimp or brine shrimp or other meaty proteins like squid, clam and mussel, as well as good marine flake or pellet food. You can also give them oyster eggs and copepods.

They like to supplement their protein meals with seaweed strips or vegetation-based flakes or pellets, giving them a good well-rounded diet.

We feed our wrasse a staple daily diet of Ocean Nutrition Spirulina Flakes and Omega One Kelp Pellets. These two daily foods plus a selection of live foods are enough to ensure they receive the correct diet in a home aquarium.

They like their food very small and will eat small meals several times a day. They have a high metabolism so are better fed several small meals rather than a couple of larger ones. You shouldn’t leave them for longer periods without someone to make sure they are regularly fed.

As they adapt well to aquariums they also adapt well to new diets, and can switch from life to frozen food. You may find that your wrasse likes to have his food thawed and even warmed in the microwave or quickly steamed, which is also very good for killing off any parasites that may have been lurking in the food.

Can the Flasher Wrasse Female turn into a Male?

If you have female flasher wrasse in the tank for too long without a make, one of the females can turn into a male for breeding purposes.

Wrasse are a species of fish called protogynous hermaphrodite, which means that all fish are born female but the dominant females turn into males as needed. If there are no males in a colony, or if your tank’s male is killed or dies, one of the females may turn into the male.

This can happen in as little as two weeks.

Will Flasher Wrasse breed in the home aquarium?

While it is technically possible, there aren’t any records of wrasse like these spontaneously spawning in home aquariums, which is one of the reasons why they are hard to come by from suppliers. In order to breed, they need a very large and tall aquarium to give them room for their natural breeding dance and spawning.

During spawning, both fish will swim rapidly upwards in a water column while releasing the eggs and milt. These will be carried by the current until the fry are free swimmers, and then they will make their way to the bottom where the breed is happier.

Are McCosker’s similar to Carpenters Flasher Wrasse?

The Carpenters Flasher Wrasse is related to McCosker’s and is generally more well known. Both fish are hardy breeds and generally easy to keep happy in their tank. Both are reef safe and are excellent fish for beginners who are just starting to find their feet (or fins) in fish-keeping.

Carpenters Wrasse- Image Credits

What Illnesses and Concerns affect the Flasher Wrasse?

All new fish should be quarantined before being introduced to an established community in your aquarium. Experts recommend letting your wrasse have a quick swim in freshwater with a pH level that matches your tank, before a day or so in the quarantine tank. He can be treated with Praziquantel in the quarantine tank to help remove any infections or bacteria.

Wrasse can suffer from Monogenean Flukes, which are tiny clear worms that eat at their skin and eyes. They can also suffer from Cryptocaryon and other internal parasites, which they can also be treated for before adding them to your tank.

McCosker’s Flasher Wrasse

These beautiful wrasse are perfectly suited to a community saltwater aquarium and as such you have a wide variety of perfect tank mates to choose from.

I kept mine with Clownfish, Dwarf Lionfish, Dwarf Angels, Pajama Cardinals, Diamond Watchman Goby and Mimic SaddleFilefish. All of which lived perfectly in a 100 Gallon Reef tank.

Your choice is endless with the fish and you’ll find they will live in a small group of females peacefully but remember to only have one male per tank or they will fight for authority in the aquarium amoungst themselves.

Final Thoughts

The best features of these fish are their flashy fins. When happy, and when courting females, or just generally showing off (they also love mirrors!) they will dart back and forth and flash as though lit from within.

Popular with enthusiasts, the McCosker’s Flasher Wrasse has lots of personality and is often a favorite in the tank. He can be picky as well as a big eater, so if you find the combination of food that he likes he will wolf it down.

Given space to play and three square protein meals a day, your little friend should thrive.

Fish owners rave about the characteristics of each of these fish, they should fit in happily with an established community (albeit one that is relatively peaceful) in your tank and hopefully give you some gorgeous displays of flashing their fins when they are content. They can be difficult to source from suppliers, but if you can, they are well worth it.

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