Scarus quoyi – Quoyi Parrotfish
Scarus quoyi was first described by Valenciennes in 1840. Their common name is Green Blotched Parrotfish, Quoyi Parrotfish or Quoys Parrotfish. The genus name Scarus comes from Latin. “Skaros” is a fish described by ancient writers as parrotfish. This in its turn comes from ancient Greek: “skairo” means to jump; the legendary jumps and tails splashes of this family were well known to ancient fishermen.
This species belongs to the Scaridae family. This family contains about 10 genera and 100 species.
Scarus quoyi is a fairly large aquarium species. They can reach a total length of 40 centimetres in the wild. In the aquarium, they usually remain somewhat smaller. This is usually because they are kept too small and don’t get enough food for their active behaviour.
Mostly only males are offered in the shop. The males are blue-green with pink edges on the scales. The colour on their flank extends upwards towards blue-green and more towards pink on the belly. The dorsal and anal fins are pink with a blue hem above. The caudal fin is trimmed with a yellow hem. The head is pink with a mask of blue-green lines. All in all a very striking and colourful species.
This species don’t start out as striking and colourful as the males. All Quoyi Parrotfish start as a female. They live in a harem with one male with several females. The male defends a territory. When the male dies, the largest and strongest female turns into a male.
Juveniles and females are coloured differently. They are pale gray-brown. Five or six faint white streaks are visible on their flanks. They have three pale stripes on their bellies.
The Green Blotched Parrotfish can be found at depths of 2 to 18 meters. They are mainly located on and around coral reefs. At high tide, they also look for the flat areas that surface during the day. Here they graze on the algae. Often a male forms a territory of many tens of square meters containing a number of females.
Their habitat extends from India along the Ryukyu Islands near Japan down to New Caledonia. They can also be found along the north coast of Australia and on the Great Barrier Reef.
In the wild, Scarus quoyi is a herbivore. They scrape their teeth over coral and rocks to eat the algae. With their front teeth, they break some bits and pieces away from the coral. The throat contains a second set of teeth that grind the coral. Loose pieces of dead coral are ground into sand. This also breaks the cell walls of the algae, making them easier to digest. The sand is disposed of through the gills. It is commonly believed parrotfish are a main contributor to the white sandy beaches in the tropics.
In the aquarium, they should at least get a lot of vegetable food. Vegetable flakes, Nori etc. are absolutely necessary. Also give them some hard food with which they can sharpen their teeth, for example, small crabs and shrimps. Because they scrape algae from dead coral, we recommend keeping them only in a large and well-established aquarium.
Because they swim around very active and fast all day long, they also need a lot of food! Many Scarus quoyi remain too small and die prematurely because they are kept too small and receive too little suitable food. They actually need food all day long, such as Masstick, Nori leaves, pallets, green food rings that you stick to the glass with a suction cup. But also target feed them with mysis, brine shrimp, the occasional mussel or small crab. If you look at the fish from above, the body should extend past their gills. If the body is in line or falls within the gills, it is much too skinny!
Due to its feeding behaviour, Scarus quoyi can only be kept in large aquariums. To ensure sufficient space and coral from which they can scrape algae, it is recommended to keep them in an aquarium of at least 1,500 to 2.000 litres. That’s for a solitary male. A harem of one male with a few females needs an even larger aquarium. Provide enough coral that they can use to scrape off some algae. Slowly they grind the coral into sand. Over time, the dead coral therefore decreases in size.
Provide plenty of open swimming space. These are very active swimmers who endlessly swim laps from one side of the aquarium to the other. They patrol the corals and reefs looking for something to eat.
Scarus quoyi sleeping bag
At night the Green Blotched Parrotfish sleeps between the rocks. They form a kind of sleeping bag made of mucus. After sunset, the body forms a kind of bag of mucus. This mucus becomes somewhat rubbery after it comes into contact with the saltwater. This sleeping bag contains a small opening so that a little bit of freshwater can still enter. The mucus layer ensures that predators such as sharks, cannot smell the Green Blotched Parrotfish at night. It also ensures that the predators cannot “see” the electrical signals of muscle movements.
Parasites are also kept away at night. When fish are sleeping, it is usually easier for them to attach to a fish. That is a lot more difficult with a protective layer of mucus.
When a predator has found a sleeping Scarus quoyi, they shoot out of their sleeping bag. The bag of mucus is left behind to confuse the predator.
In the aquarium, they do not always make this “sleeping bag”. Perhaps a lack of threat means they don’t need it?
Compatibility with other species
This active species combines well with other fish species. They usually also leave the invertebrates alone. Only a combination with other Parrotfish is not recommended. They are territorial when it comes to similar food competitors.
Coral is not eaten. However, Quoyi Parrotfish are a bit clumsy when looking for and scraping algae. They may knock over, break off or accidentally chew some coral. Usually they are fairly reef safe, if kept in an aquarium of sufficient size and the correct diet.
John de Lange
John de Lange