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Rainford's Butterflyfish

Rainford's Coralfish, Northern Butterflyfish

Family: Chaetodontidae Rainford's Butterflyfish, Chaetodon rainfordi, Rainford's Coralfish, Northern ButterflyfishChaetodon rainfordiPhoto © Animal-World: Courtesy Greg Rothschild
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Hello, My name is Linnea Rainford (just like the fish!). When I first heard about this fish, I was amazed! It seems that not only is my last name the name of a... (more)  Linnea Rainford

The Rainford's Butterflyfish is quite beautiful but is a poor eater, consequently it is very difficult to keep in the aquarium!

The Rainford's Butterflyfish Chaetodon rainfordi is a visual treat for the scuba diver as it is unafraid and easily approached. This species is endemic to the Great Barrier Reef and adjacent coastal areas, Lord Howe Island, and Papua, New Guinea. It dwells at depths of only about 3 - 49 feet (1 - 15 m) in areas of sparse coral growth but with lots of algae. This is a pretty butterflyfish that could also be a real gem in the aquarium, but unfortunately it is notorious for being difficult to feed. It is occasionally available, but is rather expensive.

This butterflyfish is moderate in size, reaching not quite 6 inches (15 cm) in length. Its body has a rounded, almost triangular shape and it is brightly colored. It is one of four species that form a distinct group of the subgenus Discochaetodon. This subgenus is restricted almost entirely to the Western Pacific and these four can only be distinguished from one another by their individual color patterns.

The color of the Rainford's is a bright yellow with a dark orange bar running though the eye followed by white bars, a curved orange band on the body, and another on the tail fin. On the sides are two broad bluish gray bands with yellowish orange along the edges. Other common names it is known by include Rainford's Coralfish and Northern Butterflyfish.

Overall this fish is notorious for being a poor eater and not overly hardy. It is one of the most difficult butterflyfish to keep in a captive environment and is best reserved for only the expert aquarist. In their natural environment they eat coral polyps, algae, and small benthic invertebrates. This diet is difficult to reproduce in the aquarium. Many have difficulty adjusting and refuse the foods offered.

It is better at acclimating when kept in a small group, or with other hardy butterflyfish that may entice it into trying substitute foods. A specimen that does start browsing in the tank, feeding on live clams or mussels, filamentous algae and encrusting invertebrates, may then take other substitute foods. To acclimate and sustain this butterflyfish will take great devotion and dedication. Even then, both initial and long term success is minimal.

This fish does need a spacious aquarium with plenty of rocky hiding places as well as open areas to swim. A 55 gallon tank is the minimum size for a single fish, and a bigger tank will be needed if you want to keep more than one. It will swim freely in the open water, but it also retreats into cracks and crevices. As it is fond of the live polyps of stony and soft corals, it can not be recommended for a reef-type setting with the exception of the more toxic soft corals. It can do well in a fish only community tank with a variety of other species with a similar temperament, as well as the larger and rather territorial angelfish like Pomacanthus and Holacanthus.

For more Information on keeping saltwater fish see:
Marine Aquarium Basics: Guide to a Healthy Saltwater Aquarium

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Perciformes
  • Family: Chaetodontidae
  • Genus: Chaetodon
  • Species: rainfordi
Rainford's Butterflyfish

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Rainford's Butterflyfish swimming around its tankmates.

Great video of a nicely colored and healthy looking Rainford's Butterflyfish. The butterflyfish is seen swimming around an aquarium, picking at some of the corals and searching for food, and swimming peacefully amongst its tankmates.

Rainford's Butterflyfish - Quick Aquarium Care
  • Aquarist Experience Level: Expert
  • Aquarium Hardiness: Difficult to Impossible
  • Minimum Tank Size: 55 gal (208 L)
  • Size of fish - inches: 5.9 inches (14.99 cm)
  • Temperament: Peaceful
  • Temperature: 68.0 to 81.0° F (20.0 to 27.2° C)
  • Range ph: 8.1-8.4
  • Diet Type: Omnivore
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Habitat: Distribution / Background

The Rainford's Butterflyfish Chaetodon rainfordi was described by McCulloch in 1923. It was first collected at Horbourne Island off Port Denison, Queensland of Australia. They are found in the Western Pacific Ocean at Queensland, the Great Barrier Reef, Lord Howe Island and southeastern Papua, New Guinea.

This species is on the IUCN Red List as Near Threatened (NT). There have been localized declines in its population corresponding to the reefs where there has been coral loss, mostly due to sedimentation and some patchy bleaching. Other common names it is known by include Rainford's Coralfish and Northern Butterflyfish.

This species is a member of a distinct group of similarly shaped butterflyfishes that belong to the subgenus Discochaetodon, which may eventually become a subgenus of the Megaprotodon group. This is a group of four species that are restricted almost entirely to the Western Pacific and can only be readily identified by their individual color patterns. The other three members are the Golden Butterflyfish Chaetodon aureofasciatus, the Eightband Butterflyfish Chaetodon octofasciatus, and the Three-striped Butterflyfish Chaetodon tricinctus. Of these four, the Eightband Butterflyfish C. octofasciatus is the most widely ranging.

The Rainford's Butterflyfish is thought to possibly be an ancestor of the more common Eightband Butterflyfish C. octofasciatus. The Eightband Butterflyfish ranges widely in the western Pacific, though not reaching Australia. These two differ in that all the stripes of the Eightband have changed to yellow under some influence of circumstance. However the distribution of the Eightband Butterflyfish does not overlap with that of Rainford's Butterflyfish. In Papua New Guinea the latter is seen in southern part and the former in the rest of the island. Another member, the Golden Butterflyfish Chaetodon aureofasciatus, co-occurs with Rainford's Butterflyfish both in Australia and southern Papua of New Guinea and a hybrid cross of the two is reproduced.

This species dwells in coastal and offshore reefs that have sparse coral growth but with lots of algae. It Inhabits rocky reefs, lagoons, and reef-patch slopes at depths between 3 - 49 feet (1 - 15 m). They are one of the most common species seen in the lagoons of Queensland. Adults are often seen in mated pairs in their natural habitat and they are also occasionally encountered in small groups. Juveniles can be observed in a group in coral rich localities. In their natural habitats these fish feed on corals, algae, and small benthic invertebrates.

  • Scientific Name: Chaetodon rainfordi
  • Social Grouping: Pairs - They are usually seen in pairs, though sometimes in small groups.
  • IUCN Red List: NT - Near Threatened


The Rainford's Butterflyfish has a laterally compressed body that is round, almost triangular in shape, and it has a protruding snout tipped with a small mouth. The dorsal fin is continuous and it has a rounded tail fin. This species can reach a total length of about 6 inches (15 cm) in the wild, but most available specimens are are less than 4 1/3 inches (11 cm). The lifespan for most of the Chaetodon species is between 5 - 7 years, but many of this species of fish do not survive in the home aquarium.

The adult C. rainfordi is yellow with white bars behind the eye. Several slightly curving orangish yellow bars run on the side, and there are two some dark bluish gray areas with dots between the bars centrally. There is an orangish area on the caudal peduncle and a yellow bar on face. The fins are yellow. Juveniles are similar but with a black spot edged by white on the caudal peduncle.

A hybrid cross of the Rainsford's Butterflyfish and the Golden Butterflyfish is observed and shipped from Australia on rare occasions. The hybridized specimens almost always have obscure bars on the side.

  • Size of fish - inches: 5.9 inches (14.99 cm) - Most specimens available are are less than 4 1/3 inches (11 cm). According to Burgess (1978), its standard length at maximum was 5 1/2 inches (14 cm) and the total one may reach is 6.3 inches (16 cm).
  • Lifespan: - The average lifespan of Chaetodon species is between 5 - 7 years, but many of this species of fish do not survive in the home aquarium.

Fish Keeping Difficulty

The Rainsford's Butterflyfish is one of the difficult Butterflyfish to keep in the captive environment. They have a poor history of sustainability as many will refuse to eat. A few specimens have been successfully encouraged to accept substitute foods. Smaller specimens under 3.9 inches (10 cm) will acclimate better than adults and do best in an aquarium with lush filamentous algae growth. Keeping it with a few hardier butterflyfish can also help encourage it to try substitute foods.

Juveniles tend to accept various foods and will be more successfully kept than adults. Keep in mind that most cases will fail. Even if it accepts some foods like algae it will not be a hardy pet and most possibly not survive. It is not recommended for reef-type aquariums as it is fond of the live polyps of stony and soft corals, with the possible exception of some of the more toxic soft corals. But if you want to keep it alive they should be provide some kinds of live coral.

  • Aquarium Hardiness: Difficult to Impossible
  • Aquarist Experience Level: Expert

Foods and Feeding

The Rainsford's Butterflyfish are omnivores. In the wild they feed on corals, algae, and small benthic invertebrates. In captivity the best chance of success is to place it in a tank with lush filamentous algae for it to browse on, and keep it with a few other hardy butterflyfish to help enticed it to accept substitute foods. You can try various live foods such as clams with their shells cracked open, live brine and mysid shrimps, and commercially prepared formulas containing algae; along with a variety of meaty foods, dried flakes, tablets, and Japanese Nori (Asakusa-nori).

As it is fond of the live polyps of stony and soft corals it can not be recommended for a reef tank, but if you want to keep it alive they should be provide some kinds of live coral. At first feed it frequently everyday then feed it at least twice a day. Juveniles and younger specimen should be fed three to four times a day.or more. In this way the chance to acclimate them may be possible.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day - Offer various foods quite frequently at first. Once acclimated adults need at least 2 feedings a day and juveniles need 3 to 4.

Aquarium Care

Though not a very quick swimmer it swims freely, usually spending a good deal of its time in the open water and moving in and out of crevices. Frequent water changes are not necessary, rather normal water changes at 10% biweekly or 20% monthly are fine. Sudden massive water changes can cause trouble, and it may be somewhat sensitive to water change.

  • Water Changes: Bi-weekly - Change 10% biweekly or 20% monthly, avoid sudden massive water changes.

Aquarium Setup

These fish need a lot of space to swim as they can reach about 6 inches in length. However it is not a very quick swimmer and seldom will it go up to the surface to take foods. Because small individuals are often recorded from the mouth of the Noosa River of southern Queensland, this species could possibly tolerate a lower level of salinity than others of its family.

A 55 gallon tank is the minimum suggested size for a single fish, though much larger tank and keeping it with companions is better. The tank should be well decorated with rocks creating many hiding places. They also need plenty of open space for swimming. This fish is a coral eater, nipping the polyps of hard stony coral species. Consequently it is not recommended for coral-rich reefs.

  • Minimum Tank Size: 55 gal (208 L) - Just 55 gallons is fine for a single fish, but having a much larger tank and being kept with companions is better for this species.
  • Suitable for Nano Tank: No
  • Live Rock Requirement: Typical Plus Hiding Places
  • Substrate Type: Mix - Sand + Coral
  • Lighting Needs: Moderate - normal lighting - It is best kept under the normal lighting conditions, but can also be kept under very bright light as long as some dimly lit spaces are provided.
  • Temperature: 68.0 to 81.0° F (20.0 to 27.2° C) - This species lives in both tropical and sub-tropical areas. Avoid temperatures higher than 84° F (29° C) or below 66° F (19° C).
  • Specific gravity: 1.020-1.025 SG
  • Range ph: 8.1-8.4
  • Brackish: No
  • Water Movement: Weak - Water movement is not a significant factor. It can tolerate a rather strong flow but a tank with slow-moving waters will be the best
  • Water Region: All - It will swim freely in the open water, but it also retreats into cracks and crevices.

Social Behaviors

The Rainford's Butterflyfish is a non-reef safe fish. Though it does well in a coral-rich tank, it will nip the polyps of hard stony coral species. It is best kept in a fish only community tank that is well decorated with rocks/ corals and many hiding places.

This species is generally not an aggressive fish. It is best to select other tank mates that are not overly territorial or aggressive. It can be kept with other butterflyfish species. It can even be kept with others of its own kind, though there will be occasional bouts where they will chase and nip each other.

it can be kept with the larger and rather territorial angelfishes like Pomacanthus and Holacanthus. Centropyge, along with other angelfish members of Apolemichthys, Genicanthus, Chaetodontoplus and Pygoplites would also be good tank mates. Smaller non-aggressive fishes like cardinalfish, gobies, tilefish, fairy basslets, fairy and flasher wrasses are also good candidates as tank mates. Small but very territorial fish like dottybacks should be avoided. Such fish as Basses or scorpionfish, even if they are small enough, should also be avoided.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species - conspecifics: Yes - They are better at acclimating when kept in a small group.
    • Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Safe
    • Semi-Aggressive (anthias, clownfish, dwarf angels): Monitor
    • Aggressive (dottybacks, 6-line & 8-line wrasse, damselfish): Threat
    • Large Semi-Aggressive (tangs, large angels, large wrasses): Monitor
    • Large Aggressive, Predatory (lionfish, groupers, soapfish): Threat
    • Slow Swimmers & Eaters (seahorses, pipefish, mandarins): Monitor
    • Anemones: Monitor
    • Mushroom Anemones - Corallimorphs: Monitor
    • LPS corals: Threat
    • SPS corals: Threat
    • Gorgonians, Sea Fans: Threat
    • Leather Corals: Threat
    • Soft Corals (xenias, tree corals): Threat
    • Star Polyps, Organ Pipe Coral: Threat
    • Zoanthids - Button Polyps, Sea Mats: Monitor
    • Sponges, Tunicates: Monitor
    • Shrimps, Crabs, Snails: Threat
    • Starfish: Monitor
    • Feather Dusters, Bristle Worms, Flatworms: Threat
    • Clams, Scallops, Oysters: Threat
    • Copepods, Amphipods, Mini Brittle Stars: Threat

Sex: Sexual differences

No sexual difference is noted for this species, however they are gonochoristic, meaning that each fish is either a male or a female and they do not change sex.

Breeding / Reproduction

The Rainford's Butterflyfish has not been cultivated in captivity. However it is known that they become sexually mature at two years of age and spawn between November and March. In the wild butterflyfish are pelagic spawners that release many tiny eggs into the planktonic water column where they float with the currents until they hatch. Once hatched the fry are in a post-larval where their body, extending from the head, is covered with large bony plates.

Marine butterflyfish have not reportedly been spawned successfully in captivity. There are, however, reports of some success in rearing wild collected larvae of some of the corallivorous butterflyfish. It is hoped these captive reared fish will be adapted to accept aquarium foods, and thus broaden the species selections that can be sustained in captivity. For more information see, Marine Fish Breeding: Butterflyfish.

  • Ease of Breeding: Unknown

Fish Diseases

Many of the Chaetodon members are often very colorful and attractive to aquarists. Unfortunately some of them are rather difficult to keep for a long period. Some are exclusively coral eaters, and sometimes they suffer from "ich" (white spot disease) and other infectious diseases. Problems with disease are reduced in a well maintained aquarium. Any additions to a tank can introduce disease, so it's advisable to properly clean or quarantine anything that you want add to an established tank prior to introduction.

Diseases that marine Butterflyfish are susceptible to include Marine Ich(white spot disease), Marine Velvet, Uronema marinum, and Lymphocystis. Some can be treated successfully with medical care or copper drugs, but some species hate sudden changes of water including PH, temperature, or any drug treatment. In the wild a cleaner wrasse (Labroides sp.) will help them by taking parasites from their bodies, however these wrasses are extremely difficult to sustain in captivity. Alternative fish such as Neon Gobies (Gobiosoma spp.) can help them by providing this cleaning service in the home aquarium.

The Rainford's Butterflyfish is a stony coral eater. Even if it accepts some foods like algae it will not be a hardy pet and most possibly not survive. It can also be sensitive to some drugs. Be sure to observe this fish closely when medicating it, so you can remove it if it shows signs of stress. For information about saltwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.

"I have kept one adult individual of some 8 cm in a fish community tank, but this beautiful butterflyfish denied any food and starved to death." ...Hiroyuki Tanaka


The Rainford's Butterflyfish are occasionally available at retailers on line, and sometimes in pet stores. Most are smaller than 4.3 inches (11 cm), but juveniles less than 2 inches (5 cm) are rare. It is a somewhat more costly butterflyfish and prices will vary depending on the size.


Author: Hiroyuki Tanaka, Clarice Brough CFS
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