Chevron Tang
Chevron Tang
 

Chevron Tang

Ctenochaetus hawaiiensis


Chevron Tang
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The fish species Ctenochaetus hawaiiensis is known under several different common names in English, such as Chevron tang, Chevron, Black surgeonfish, Hawaiian surgeonfish, Hawaiian bristletooth, and Hawaiian kole.

Ctenochaetus hawaiiensis has not been evaluated for the IUCN Red List of Threatened Species.

Geographical range, habitat and habits

The Chevron tang is found throughout most Oceania. Its range stretches from Micronesia, Wake and Marcus to Hawaii and Pitcairn.

The Chevron tang inhabits seaward rocky or coral reefs at a depth of 3-200 feet / 1-61 meters. Juveniles are solitary and prefer relatively deep areas with rich coral growth. Adults live in small groups and tend to stay in shallower waters; they are especially fond of highly oxygenated surge areas. Adults are typically found among rocks and boulders and are known to maintain bonded pairs.  

Size and appearance

The largest scientifically measured Chevron tang was 25.0 cm / 9.8 in.

The juvenile fish is bright orange-red and decorated with numerous variegated bright blue or purple-blue lines. These lines form chevrons (multiple Vs joined together, e.g. VVVVVV.) The fins have a violet tinge and become bright blue posteriorly, right above and below the caudal peduncle. Compared to the adult fish, the juveniles have deeper bodies.

All members of the genus Ctenochaetuschange colours as they mature, but the transition is especially noticeable in the Chevron tang. Adult fish will seem uniformly black or brown when viewed form a distance, but if you look closer you will be able to see dark green-blue horizontal pinstripes on a dark orange-red background.

On each side of the caudal peduncle, there is a spine which is used for defence or to establish dominance. When the spine is not needed, the fish will keep it folded down inside a groove. The spine is commonly referred to as “scalpel”, hence the name surgeonfish.

Unlike most of the other members of the family Acanthuridae, the Chevron tang has only 8 dorsal spines, not 9.

Chevron tang care

The Chevron tang is one of the smallest and also one of the least active members of the surgeonfish group, but this doesn’t mean that it is a suitable choice for small aquariums. The aquarium must be large enough to fit plenty of rockwork as well as give the fish a lot of free space to swim around in. It is not advisable to house this species in an aquarium smaller than 75 gallons / 285 litres. In a smaller aquarium, it is difficult to provide the fish with sufficient amounts of accumulated detritus and naturally growing algae.

Ideally include both live rock and live sand in the set up. The set up must also include crevices where the fish can seek shelter during the night. The Chevron tang is a dedicated algae eater and will spend most of its waken hours grazing algae from various surfaces in the aquarium.

The recommended water temperature is 73 -80° F (23 - 27° C). Keep the pH-value between 8.1 and 8.4 and the specific gravity at 1.020-1.025. As mentioned above, adult Chevron tangs are primarily found in oxygen rich waters, such as surge areas, and you must therefore keep the aquarium very well oxygenated. Strong circulation is recommended.

The Chevron tang is only a tad aggressive and can be successfully kept in community aquariums with peaceful species. Generally speaking, avoid keeping it with fish that has a similar body shape, colour pattern or diet. The Chevron tang is often housed with other peaceful tangs that do not compete with it for food, e.g. the sailfin tangs of the genus Zebrasoma. It should however be noted that tangs can be territorial towards each other, so keep an eye on them. 

The Chevron tang will leave corals and invertebrates alone and is considered reef safe. Large specimens may cause minor injury to corals while feeding, but this rarely becomes a problem.

Just like the other surgeonfishes, the Chevron tang is equipped with a “scalpel” spine and it is important to be careful when handling this fish. The spine is comparatively small, but it can still cause discoloration and swelling if you are cut. The pain is known to last for hours and there is also a high risk of infection.

Chevron tangs will normally tolerate a short treatment with medicines containing copper, but prolonged treatment can be harmful since it might disturb the necessary microfauna found inside their digestive system.  It should be noted that members of the family Acanthuridae do not produce a lot of skin mucus and this makes them more vulnerable to skin parasites, e.g. marine ich. In the wild, they will normally seek out cleaner wrasse from the genus Labroides to get rid of external parasites. Since wrasses are difficult to keep in aquaria, you can instead provide your tang with other good cleaners, such as cleaner shrimp or Neon Gobies (Gobiosoma spp.).

Feeding Chevron tang

Instead of the filamentous algae eaten by other tangs, the Chevron tang feeds primarily on detritus rich in minute algae. The habit of eating another type of algae than the other tangs has of course made this species attract the interest of hobby aquarists battling excessive algae growth in their marine aquariums.

The Chevron tang belongs to a group of fishes known as bristle-tooth / comb-tooth tangs due to their nature of feeding; the members of the genus Ctenochaetus. Inside the mouth of a Ctenochaetus fish, you will find several rows of numerous small and flexible teeth (up to 30 teeth). The mouth itself is protrusive and gives the fish a characteristic pouting look. The Chevron tang use its teeth to continuously lift and sift through detritus and other types of algae material deposited on sand, rocks and other surfaces. The protrusive mouth works just like a vacuum cleaner and it can actually be possible to see lip marks on the aquarium glass where algae once used to be.    

In the wild, the Chevron tang will spend most of its time sifting through food and this should be taken into account when feeding this species in the aquarium. Unlike a predatory fish that might catch a prey once in a while and go without food for many hours or even days and weeks, the Chevron tang should be fed many small portions throughout the day instead of just one or two big meals.

If not provided with a suitable diet, the Chevron tang can loose its colours. It will also be more disease prone and may for instance develop lateral line disease. Natural algae growth should be encouraged in the aquarium and it is important to allow detritus to build up. Unless you have a huge aquarium, the naturally occurring food will not be enough for your Chevron tang – you have to supplement to keep it happy and healthy.

The Chevron tang is often referred to as an herbivore fish, but detritus actually contains some meaty foods as well and you should therefore give your fish occasional servings of suitable meaty foods in the aquarium. The bulk of its diet must however be herbivore. You can for instance feed your Chevron tang plenty of marine algae and boiled vegetables (e.g. broccoli and zucchini) plus occasional servings of brine shrimp and mysid shrimps. The Chevron tang loves to feast on noori; you can use a vegetable clip or a clothes-pin to avoid having noori drifting around in the water. It is also a good idea to add a high-quality flake food, preferably with spirulina and plenty of vitamin C, to the diet.

Breeding Chevron tang

It is hard to sex Chevron tangs based on outer appearance.

The Chevron tangs carry out pair spawning and adult fish are known to maintain bonded pairs in the wild. 

This species is not known to have been successfully bred in aquariums.

Surgeonfish - Tang Articles:

Achilles Surgeonfish – Acanthurus achilles
Atlantic Blue Tang – Acanthurus coeruleus
Blue Hippo Tang – Paracanthurus hepatus
Clown Surgeonfish – Acanthurus lineatus
Convict Surgeonfish – Acanthurus triostegus
Desjardinii Tang – Zebrasoma desjardinii
Kole Tang – Ctenochaetus strigosus
Mimic Surgeonfish – Acanthurus pyroferus
Naso Tang – Naso lituratus
Orangeshoulder Surgeonfish – Acanthurus olivaceus
Powder Blue Tang – Acanthurus leucosternon
Powder Brown Tang – Acanthurus japonica
Purple Tang – Zebrasoma xanthurum
Sailfin Tang – Zebrasoma veliferum
Scopas Tang – Zebrasoma scopas
Whitecheek Surgeonfish – Acanthurus nigricans
Yellow Tang – Zebrasoma flavescens


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