| Read some selected articles from recent issues |
| Are Fish Intelligent ? - School for Thought by Dave Wolfenden |
Introduction
HOW intelligent are fish? Widely regarded as being mere aquatic simpletons with very little keeping their ears apart, fish have a bit of a bad image when it comes to how much they have ‘up top’!
But is that fair? Probably not, and to a great degree it’s a reflection of our cultural ‘mammal-centric’ bias towards our furrier relatives; many biologists still classify fish (rather insultingly) as ‘lower vertebrates’, which can’t help their image either. In reality, fish are certainly a lot smarter than they are given credit for, but the first problem with asking the question of how intelligent fish are is that it tends to generate a rather awkward question itself – that is, ‘What is intelligence?’.
This is actually surprisingly difficult to answer... Is it related to memory? Perhaps the ability to learn or solve problems defines intelligence? Or, does it extend into concepts such as the ability to manipulate the behaviours of others? Well, probably all of these are important; we can certainly consider all of these factors and see how fish perform, and there’s been a fair amount of (often very ingenious) research carried out into this subject. The results can often be surprising...
Three Second Memory?
We’re all familiar with the well-worn cliché that fish have a ‘three second memory’, as exemplified by the scatty (but endearing) regal tang (Paracanthurus hepatus) ‘Dory’ of Disney’s ‘Finding Nemo’. But how accurate is this famous ‘fact’? Well, not very, and it’s not exactly clear where this one originated; it just appears to have become engrained in the collective unconscious for some reason – in any case, it’s patently not true, so let’s put that one to rest right now! (By the way, just for the record, there’s no evidence to suggest that regal tangs are any more, ahem, ‘intellectually challenged’ than any other fish.)
The memory ‘window’ is the length of time that an animal remembers a particular piece of information for (such as information gained during foraging), and although where fish are concerned, it does tend to vary between species, it is certainly much more than three seconds! Experiments on various fish species have demonstrated that they are able to memorise information often for several weeks, but this depends on the species and the relevance of the information.
Memory is, of course, crucial to learning (which we could define as ‘a modification of behaviour based on experience’), and fish can learn – but sometimes we need to devise novel ways of allowing them to show us what they can do. To assess the ability of animals such as laboratory rats to learn, it has been traditional to use mazes; Roger Hughes and Christine Blight of Wales’ University of Bangor did just this with two rocky shore fish species, the corkwing wrasse (Crenilabrus melops) and the fifteen-spined stickleback (Spinachia spinachia) in a series of fascinating experiments. The maze itself was located in an aquarium, and was actually ‘radial’, looking something like a spoked wheel, with a central chamber linked to eight long ‘arms’.
At the end of each arm, opaque feeding cups were placed, each containing a single Mysis shrimp
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Hughes and Blight were initially interested in how efficiently the test subjects could forage in the maze when no visual identifiers were available for the fishes to distinguish between any of the arms – of course, foraging efficiently in this case means not visiting any of the arms which had been previously had their food eaten. (Simply visiting arms randomly is pretty inefficient, as the fish may revisit arms from which they have just fed, and so which will lack food.)
Interestingly, both species tended to adopt the general strategy of using an algorithm – effectively a ‘programme’ – to determine which arm was visited, and that programme was actually very simple; it instructed the fish to visit every third arm in the radial maze, which is, undoubtedly, an efficient way of foraging in such an environment.
This doesn’t appear, however, to be learned behaviour, but simply a ‘default’ feeding strategy – but a successful one, nonetheless. When visual cues were added in the form of a different coloured tile in each of the arms, the fishes’ foraging became much more efficient, demonstrating that the fish learned the visual information and adapted their foraging accordingly, the visual cues allowing them to learn which arms would lack food.
A further refinement placed the fish in the central chamber for a delay after each foraging bout. The results showed that the ‘working’ memory (giving information about the location of food in their immediate environment) for both sticklebacks and wrasse varied between 30 seconds and five minutes, which might not sound that impressive to us, but it’s all the fish need for efficient feeding in their rapidly-changing coastal environment, where food distribution changes relatively rapidly.
Another variation of the experiment involved replenishing certain cups after the fish had eaten the Mysis; the fish adapted their foraging accordingly, and were able to distinguish between ‘renewable’ and ‘non-renewable’ food sources (cups which the researchers topped up after feeding, and those which were left empty). When food was present in none of the arms or all of them, a strategy of so-called ‘win-shift’ or ‘lose-shift’ was adopted, whereby the fish moved on to other arms. If particular cups were replenished whereas others were not, the fish quickly learned to adopt the tactic of ‘win-stay’ to exploit the renewable resource.
These fascinating experiments offer plenty of further scope into studying the capacity of fish to remember and learn...
Mental Maps
A fascinating series of experiments by an American animal behaviour researcher, the late Lester Aronson, demonstrated the remarkable ability of the Atlantic frillfin goby Bathygobius soporator to learn its surroundings. To understand the significance of this, it’s important to appreciate that, being a rock-pool dweller, there are two main dangers affecting these fish; the constant threat of predation and the occasional danger of their pool drying up.
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When faced with these dangers at low tide, the gobies have the ability to jump from one pool to the next, often performing a series of jumps via a number of pools into the sea and, of course, (at least temporary) safety. It’s clearly vital that the gobies are able to jump to the right spot, as the consequences of a misjudged jump could be fatal.
In order to test how the gobies achieve this feat, Aronson’s ingenious experiment artificially replicated three small tidepools adjacent to a larger main pool (representing the sea), and the water level could be altered to mimic high and low tides. When prodded with a stick (a not particularly elegant, but undoubtedly effective, way of simulating danger!), fish that were exposed to all the tidepools at the simulated high tide successfully jumped to the safety of other pools and into the main pool when the water level was dropped (thus separating each pool from the others).
Crucially, fish which weren’t exposed to ‘high tides’ and were only kept in one of the smaller pools failed to achieve the jumps to adjacent pools. Clearly, the fish are learning something (quite what, we don’t yet know) about their surroundings during high tides for use later on, a phenomenon known as latent learning.
It’s not just rockpool fish which can learn about their surroundings; Ernst Reese of the University of Hawaii has studied so-called ‘spatial learning’ in butterflyfish (family Chaetodontidae). He noted that corralivorous butterflyfish, whilst out on foraging expeditions, followed predictable paths. Supposing that the fish were using remembered landmarks, he removed coral heads (which are obviously prominent structures in the reef environment) along the routes of particular fish; the subsequent results showed that, on their next foraging bout, the fish stopped at the site of the former coral head and appeared to search for it, and then if they were deflected from their normal route, the butterflyfish continued on their usual path at the first prominent landmark; compelling evidence that the fish have learned and remembered key features of their surroundings.
So much for memory and spatial learning; one of the more complex, and often incredibly subtle, aspects of fish cognition is social intelligence. Arguably the most interesting aspect of this topic is ‘Machiavellian intelligence’, which could be considered a ‘higher’ ability of animals; named after the Italian politician and (apparently cynical) Renaissance Man Niccolò Machiavelli, it’s concerned with the cunning exploitation and manipulation of others in social settings. But surely mere fish couldn’t be capable of that? Well, yes they are, and we can look to cleaning symbioses on the reef for a tantalising glimpse into just how scheming they can be...
Cunning Cleaners
The cleaner wrasse Labroides dimidiatus has evolved to exploit a highly unusual food resource on the reef – the dead skin and parasites of other fish! The cleaners adopt a distinctive ‘uniform’ of blue and black stripes (the blue seemingly a unique shade, widely suspected by many scientists of only belonging to cleaners) and perform a distinctive ‘dance’ to attract ‘clients’.
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At first glance, the interactions between cleaners and clients appear to be straightforward harmonious partnerships; nothing complicated, and both parties benefit from the partnership. In reality, there’s a battle going on between each party, which requires some form of intelligence to win – cleaners can benefit by ‘cheating’ (or opportunistically taking some of the client’s nutritious mucus coat instead of parasites or dead skin – painful for the recipient), and some predatory clients can benefit by actually eating the cleaner!
So, some smart (and very cunning) behaviour has been observed in fascinating studies by Redouan Bshary and colleagues... Some fish are, of course, predatory, whilst others are non-predatory; cleaner wrasse are able to differentiate between these types of fish, and behave accordingly – they never cheat on predators (why risk getting eaten?) but non-predators may be cheated. In fact, they seem to actively ‘schmooze’ the more dangerous predators by performing ‘pre-clean massages’ to the clients’ backs with their fins, a behaviour used to a lesser extent with non-predators; the behaviour may, in fact, have a variety of purposes.
The really smart aspect of cleaner behaviour is that they are able to distinguish between ‘resident’ non-predatory clients (which only have access to that one cleaner) and ‘non-residents’ (whose range includes other cleaners) – interestingly, non-residents are ‘serviced’ in preference to residents (non-residents being able to visit other cleaners if they don’t receive an adequate, prompt service).
If a cleaner cheats either of these clients, the clients themselves actually behave differently, with residents chasing the cleaners in punishment (which makes the cleaners cooperate better in future); non-residents simply swim away, and will tend to frequent different cleaning stations for a while; this is, of course, bad for ‘business’ as far as the cleaner is concerned... Potential clients waiting for a clean actually learn through observation and eavesdropping, and take a cue from the reactions of others being serviced – they allow cleaners to ‘do their thing’ if others seem to have had a positive experience, but swim away if an interaction has ended in the cleaner being chased; cleaners therefore appear to be less likely to cheat if bystanders are present!
Bshary estimates, based on extensive observations, that each cleaner wrasse is capable – incredibly – of individually recognizing over a hundred clients, recalling how their last ‘session’ ended – not bad considering each cleaner performs a total of about two thousand ‘services’ in a typical day! To round off, if you still think fish aren’t clever, this might change your mind – cleaner wrasse will sometimes bite non-predatory clients if a predator is near; as soon as the disgruntled client attempts a punishment chase, the crafty cleaner swims towards the predator, with whom it gets ‘touchy-feely’ via a back massage! Of course, in this case, the bitten client is not in a position to admonish the biter, for fear of being attacked by the predator – the wrasse is, therefore, let off the hook!
So, despite their popular image, fish can remember, learn – and even be scheming and manipulative, but we have only just begun to appreciate that fish could actually be intelligent, and we’ve only just started to investigate to what extent. Without question, the coming years are certain to bring some more startling insights into this fascinating branch of fish behaviour. Watch this space... |
| Propogating Mushroom Corals - A Piece Of Cake |
Introduction
With I imagine very few exceptions every reef tank in this country
will have at least one species of Mushroom Coral.
The Latin names for these corals are usually Actinidiscus, Discosoma,
Rhodactis, Ricordia to name but a few. The common names don't really
help much apart from aiding the hobbyist to know what colour or shape
mushroom coral they are buying, e.g. watermelon, furry, green furry,
knobbly, spotted, again the list goes on.
The fact is that what ever species of Mushroom Coral you have, they
are a piece of cake to propagate and, without putting too finer a
point on it, it is simply a matter of cutting off the head, cutting
this into four and wait for it to heal and attach before cutting it
again.
General Information
Mushroom Corals grow well and reproduce naturally on their own in
favourable conditions. This natural reproduction can take several
forms dependant on the species and individual coral. Some species
will reproduce by stretching their foot away from the coral base,
anchoring the tip in place and then retracting the foot, leaving the
tip in its new location.
The length of stretched foot will eventually tear completely. The
blob of foot budded off will very quickly transform in shape, size
and colour and within three weeks will be a perfect miniature mushroom.
Other species simply tear themselves in half by stretching their mouths
until they divide themselves in two. Again the healing process is
very quick and within a matter of weeks the two halves will be perfect
mushrooms. |
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However the method of propagation I am going to describe
will turn one mushroom into five in usually no more than three weeks
and will enable you to have propagated corals that are not attached
to the same piece of rock, allowing you to establish new colonies
in your own system, or trade your corals with other hobbyists.
In this article I am taking for granted that your reefs system is
running well and all water parameters and conditions are within "standard"
parameters (if there is such a thing).
The two points I would make is that in my experience the addition
of iodine to the tank makes Mushroom Corals grow larger and quicker,
stand up off the rock more (making propagation easier) and generally
look healthier.
Secondly, mushroom corals hate being moved, even if just from one
end of the tank to the other and they may take up to a week to return
to their usual size.
Tools/Equipment
Needed
• Sharp Pair of
Scissors
• Small Container Tank Water (Jam Jar for example, in which
to temporarily place the cut mushroom heads)
• Kitchen Roll
• Shallow Dish (The size of this dish will be dependant on the
size of your tank. I use a shallow Tupperware container. Anything
will do as long as it is food quality plastic, and will fit into the
space you have for it in your tank.)
• Rock Chippings/Crushed Shell
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The
Propagation Method
Select a healthy Mushroom Coral and with the scissors cut the mushroom's
head off. Take the cutting æ of the way down the stem. Place
the cutting into the container with the tank water. Continue to cut
as many mushrooms as required. I usually take four or five at a time.
††A good tip here is to remove the mushroom rock
from the tank if possible and hang this rock upside down over the
container, the corals will hang down from the rock and when cut will
drop straight into the container of tank water, making cutting these
corals quick, easy and not too messy. If you have handled these corals
you will know that they are very slimy and handling them can become
tricky, so this method works very well.
The foot or base of the Mushroom Coral that you have left on the rock
will, over a period of a week to ten days, begin to heal. It will
also form the basic mushroom shape and then develop its mouth. It
will take up to a further fortnight for the colour to be produced
and the foot to have changed into a brand new mushroom - ready to
be propagated again!
Prior to taking the cuttings prepare the shallow dish. This is the
container that your cuttings will spend the next month or so in, allowing
them to heal and attach themselves. Cover the bottom of the container
completely with the rock chippings or crushed shell. Fill the container
with tank water. You are now ready to complete the propagation process.
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Remove your Mushroom Coral from the holding
container and place it on a sheet of kitchen roll. The kitchen roll
soaks up any additional water released by the coral, as well as the
mucus the coral excretes.
This will make the next stage of the process a little bit easier.
These few seconds drying and exposure to air do not cause any damage
to the coral. Once you are ready, pick up the Mushroom Coral and with
one clean cut, cut the coral in half.
Repeat the procedure with the two halves. The Mushroom Coral is now
in four segments, like pieces of cake. These cuttings can now be rinsed
in the container of tank water and then placed into the shallow container
ready to go into the tank.
Once you have completed cutting and the segments of coral are in the
shallow container, return the container to your tank. Place it in
an area of relatively low water movement. The idea being that the
container prevents the cuttings from being blown about the tank and
allows them the time required to heal. It also keeps them in constant
contact with the rock chippings or crushed shell allowing them to
attach.
Within a week you will notice the cuttings swelling and becoming more
of a complete circle again. Within a fortnight they are usually attached
to the rock chippings, looking extremely healthy and are usually at
least 80% healed. Within another week they will look like they have
never been touched. At this stage they can be attached to a larger
piece of rock. Milliput or Super Glue (Cynoacrylic) is ideal for attaching
the rock or shell chippings to another larger piece of rock or coral
plug.
Final Thought
The resilience, healing and growing powers of these corals never ceases
to amaze me and I would have to say they are one of the easiest corals
to propagate. I have never experienced any problems with the many
different species I have propagated. |
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| New Species - Marine World's Butterfly Fishes |
In an attempt
to break new ground and provide readers with some exclusive
material on the amazing butterflyfishes, Marine World, in conjunction
with Vincent Hargreaves, has had a team of divers spend a week
in Western Australia looking for rare specimens to photograph.
Not only does this series of articles include some amazing photographs
of some of the world’s best underwater photographers but
we are also pleased to be the first magazine to report on a
new species of butterflyfish which is currently being described.
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There are currently 125
valid species in this family and I intend to describe and illustrate
all of them over the coming months. The series should prove
to be a valuable reference work for the future, so you should
keep the copies of Marine World safe in a binder! In this article,
the first 12 species are described. If any reader has a photograph
of an unusual species of butterflyfish, or would like to identify
the species they have in their tank, I can be contacted by e-mail
at atollreef@aol.com.
General
information
Butterflyfishes belong to the family Chaetodontidae. This encompasses
a group of fishes with striking characteristics. Generally,
they are disc-shaped and strongly compressed with deep bodies,
and high backs. The snout is often elongated and the mouth is
armed with tiny brush-like teeth (hence, Chaetodon = bristle
teeth). There is a single, continuous dorsal fin without a notch
between the spinous and soft parts. Butterflyfishes rate amongst
the most colourful fishes on the reef. Most species have a black
vertical bar running down the head and through the eye. It is
thought that this serves to confuse predators. This, along with
a prominent black ‘eye spot’ that many species exhibit,
serves to mislead an attacking fish into thinking it is aiming
for the head when, in fact, it is the tail. The ruse is then
complete when the butterflyfish darts away in a totally unexpected
direction.
Adult fishes are often seen on the reef during the day, usually
singly or in pairs. Juveniles, on the other hand, are frequently
encountered in small groups of up to twenty individuals. At
night, many assume a shadowy night time colouration and retire
into a nearby crevice or hole between the corals. This hiding
place is arbitrary and is simply the nearest safe haven at nightfall.
All of these species are essentially shallow water fishes that
inhabit reef shallows, lagoons, back-reef areas and coral pools.
Some may venture down to depths of over 100 feet (30 metres)
but this is not common. The exceptions to this include the Lemon
butterflyfish (Chaetodon miliaris), which is found on the reefs
of the Hawaiian Islands. Using a submersible, scientists found
this species at depths of over 830 feet (250 metres).
Their diet is very varied but usually consists of benthic algae
along with small anemones, coral polyps, polychaetes, crustaceans
and various minute invertebrates and plankton. Their elongated
snouts are specifically developed to enable them to forage for
food between the coral heads and rocks. In a single feeding
foray, a pair of fish can cover a vast area of the reef.
Knowledgeable readers will notice that I have omitted the so-called
Chaetodon andamanensis Kuiter & Debelius, 1999. Until DNA
analysis proves otherwise, I regard this is as an invalid species
and I place it in the synonymy of Chaetodon plebeius. My reasons
for doing so will become apparent when C. plebeius is discussed
in a later article.
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Chaetodon adiergastos
Seale,
1910
Common name
Philippine butterflyfish
Natural habitat:
Around soft coral on coral reefs, usually in pairs or small groups,
in the Indo-West Pacific from the Ryukyu Islands to Australia and
including the Philippine Islands and Indonesia.
Maximum adult size
6.3 inches
(16cm)
Description
The body colour is white with thin diagonal brown stripes on
the sides. The dorsal, anal and pelvic fins are yellow and the soft
portions of the dorsal and anal fins have brownish-black margins.
The caudal fin base is yellow, which extends roughly half its length.
After this there is a narrow brownish black bar leaving the rest of
the fin transparent. Young fish have a black ocellus that fades with
age. There is a broad black eye bar and a large dark blotch on the
nape.
Aquarium suitability
This is a surprisingly easy butterflyfish to keep in an aquarium,
but unfortunately it is not often imported. If it is housed in a reef
tank, it will not do any damage to stony corals once it has got used
to its normal aquarium feeding regime. Despite this, it should not
be housed with arborescent forms of soft coral, such as Nephthea and
Alcyonium species.
Chaetodon argentatus
Smith
& Radcliffe, 1911
Common names
Black pearl butterflyfish,
Silver butterflyfish
Natural habitat
Central Indo-Pacific to the Indo-West Pacific in pairs or
small aggregations in areas of dense coral growth.
Maximum adult size:
8 inches
(20cm)
Description
The body is laterally compressed and silvery white in color, with
some scales edged in black. A black bar is present through the eye
but is often indistinct. A second bar from the dorsal to the pectoral
base is clearer. A wide mid-body bar ends halfway down the side and
the fourth bar, much clearer defined, extends across the caudal base
from the soft dorsal to soft anal fins. The belly is often bright
yellow in juveniles and there are two dark bars on the tail.
Aquarium suitability
Does quite well in a large enough aquarium and is one of the hardier
species of Butterflyfishes. It is sometimes inclined to be aggressive
towards its smaller relatives. Most foods are accepted but a particular
favourite is frozen adult brine shrimp.
Chaetodon assarius
Waite,
1905
Common names
West Australian butterflyfish, Western
butterflyfish.
Natural
habitat
In small schools on rocky reefs and sandy seagrass beds of the Southeast
Indian Ocean. It is endemic in Western Australia from the Perth area
to Shark Bay.
Maximum adult size
5.1 inches (13cm)
Description
This is a close relative of Chaetodon guentheri from Southeast Australia.
There is a broad white-edged black bar through the eye and the body
is Tan or white in juveniles. The dorsal fin is dusky yellow and has
a white-edged black ocellus on the soft portion that reduces in size
with age. The base of the anal fin and caudal peduncle are dark ochre
and the anal fin has a black submarginal border. There are five narrow
bars that run vertically from the base of the spinous dorsal fin to
the mid-body region roughly level with the eye. The pelvic fins are
translucent or white.
Aquarium
suitability
Not often imported into Europe or the United States. Nevertheless,
this is a relatively easy fish to keep and feed. It should be provided
with a tank containing plenty of live rock on which it can graze.
Its natural diet consists of plankton, algae and the tiny invertebrates
that are ingested with this. This is one of the butterflyfishes that
can be kept in a mature reef tank.
Chaetodon aureofasciatus
Macleay, 1878
Common names
Golden butterflyfish, Golden-striped
butterflyfish
Natural habitat
Indo-West Pacific from New Guinea, Australia from the Great Barrier
Reef to Western Australia and Melanesia. Usually encountered singly
or in pairs in inshore reefs and coastal areas.
Maximum adult size
5 inches (12.5cm)
Description
The closest relative to this fish is C. rainfordi with which it
bears many similarities. In this case though, there are no bars
on the body and the median and pelvic fins are bright yellow. Like
C. rainfordi, there is a black-edged orange bar through the eye,
although this is not joined at the nape.
Aquarium suitability
This fish is not suitable for a reef tank because its natural diet
comprises coral polyps as well as algae and other benthic invertebrates.
Although it is capable of withstanding high changes in the specific
gravity of seawater (it is often encountered in river mouths and
estuaries) it is difficult to get to feed. Live blood worms (Enchytrae)
seem the best bet at the start, followed by frozen ones from your
pet supplier. After that, it’s only a matter of time before
they accept other foods.
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Chaetodon auriga
Forsskål, 1775
Common names
Threadfin butterflyfish, Golden butterflyfish,
Threadfin, Diagonal butterflyfish
Natural habitat
Entire Tropical Indo-Pacific and Red Sea in back reef areas, lagoons
and reef channels. They are found singly or in pairs in the reef
shallows to depths of up to 35 feet (10 metres).
Size
8 inches (20cm)
Description
The Threadfin butterflyfish is common throughout its natural range
and is easily befriended by divers offering morsels of food. Adult
specimens have a long dorsal filament. Specimens from the Red Sea
lack the ocellus on the soft dorsal fin and the dorsal filament
is shorter. Young fish have a bright yellow dorsal area, which extends
down across the caudal peduncle onto the soft portion of the anal
fin.
Aquarium suitability
This is one of the easiest of all the Butterflyfishes to
keep. The aquarium should be large enough and have plenty of hiding
places into which it can retire at night. Provide good water quality
and an assortment of frost foods in its diet and this fish will
flourish.
Chaetodon auripes
Jordan & Snyder, 1901
Common names
Oriental butterflyfish, Gold butterflyfish
Natural habitat
Rocky reefs from Japan to Taiwan in coastal areas, sometimes
where the water temperature is as low as 50o F (10o C.)
Maximum adult size
8 inches (20cm)
Description
Young fish have a black ocellus on the sort dorsal fin,
which disappears with age. The snout is silver to bluish-grey and
there is a black eye band present. Behind this eye band there is
a broad white bar that extends from the nape to the base of the
opercle. This white bar has caused much confusion in the past between
this species and C. collare. However, C. auripes has a yellow-gold
body colour with narrow horizontal stripes. The caudal fin is yellow
with a submarginal black bar and the soft portions of the dorsal
and anal fins have black margins with white sub-marginally.
Aquarium suitability
Although this species is seldom imported it settles down
well to aquarium life. It is robust and eager to accept most foods
that are offered once it feels happy with its new surroundings.
In the wild, it feeds on benthic invertebrates such as polychaetes
and coral polyps. In a tank environment though, it will accept krill,
mysid shrimp, Artemia, frozen plankton and finely chopped shellfish.
Chaetodon austriacus
Rüppell, 1836
Common name
Blacktail butterflyfish
Natural habitat
Found in areas of dense coral growth throughout the Western
Indian Ocean and Red Sea. Juveniles form small aggregations in and
around a single coral head.
Maximum adult size
5.1 inches (13cm)
Description
Easily confused with C. melapterus and C. trifasciatus. However,
in this case the anal and caudal fins are black with yellow margins
in adults. Juveniles are less colourful than their adult counterparts.
They have a large yellow-edged ocellus on the caudal peduncle. The
dorsal fin is white with a submarginal border of black in the soft
dorsal portion. There is a black bar through the eye and a second
bluish-grey bar from the dorsal base to the lower angle of the operculum.
The body colouration is predominantly yellow with narrow, bluish
stripes that are intense dorsally, becoming indistinct ventrally.
A broad horizontal daub of black is present in the third stripe
towards the posterior dorsal region.
Aquarium suitability
Feeds almost exclusively on coral polyps, therefore it is
difficult to get to feed in an aquarium. Occasional specimens have
been coaxed onto alternative aquarium foods and these do well. However,
this is the exception, rather than the rule.
Chaetodon baronessa
Cuvier, 1829
Common name
Triangular butterflyfish
Natural habitat
Western Pacific to central Indo-Pacific. It is common on
the Great Barrier Reef and is usually encountered in pairs in reef
shallows.
Size
6 inches (15cm)
Description
The body carries a series of chevron markings and the margins
of the dorsal, anal and ventral fins are chrome yellow. There are
three vertical bars on the head and the snout is often dull orange.
It is easily confused with Chaetodon triangulum. However, C. baronessa
lacks the yellow-edged triangular mark on the tail.
Aquarium suitability
Although this species is reported to be quite difficult to
keep, the fat and healthy specimen shown here had, at the time this
photograph was taken, already spent two and a half years in an aquarium.
Its diet consisted of a variety of frozen foods supplemented with
flake food and it did little if any damage to the live corals in
the aquarium. Nevertheless, this species will not tolerate high
nitrate levels.
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Chaetodon bennetti
Cuvier, 1831
Common name
Bennett’s butterflyfish
Natural habitat
Juveniles are found in reef shallows and lagoons, sometimes
in small groups of four or five individuals. Adults are usually
encountered singly or in pairs on outer reef slopes.
Maximum adult size
7 inches (18cm)
Description
The overall body colouration is bright yellow and there
is a blue-edged black bar through the eye. Juveniles have a white-edged
black lateral ocellus below the spinous dorsal fin. As the fish
grows, the white margin turns to deep blue. Two broad blue lines,
which are widely separated, curve upwards from the base of the anal
fin and finally converge at the upper angle of the gill cover. A
dull orange bar is present across the caudal peduncle.
Aquarium suitability
This species feeds exclusively on coral polyps and is extremely
difficult to feed in captivity. Limited success has been achieved
by spreading chopped squid and krill on live rock, in order to induce
the fish to feed. Nevertheless, this is perhaps one of the species
that is better left on the reef.
Chaetodon blackburnii
Desjardins, 1836
Common names
Rayed butterflyfish, Brownburnie
Natural habitat: Coral reefs on outer reef slopes in the Western
Indian Ocean from Kenya to Mauritius and Madagascar.
Maximum adult size
5.1 inches (13cm)
Description
Juveniles have dark brown bodies with bright yellow on and
behind the operculum. Adults are somewhat lighter in colour and
the opercular region is often brownish-yellow. There is a dark eye
bar present and the caudal fin is white with a translucent margin.
Six or more diagonal bars adorn the sides of the body, but these
are not so readily apparent in juveniles. The dorsal and anal fins
are brownish-black and the pelvic fins are bright yellow.
Aquarium suitability
Not often imported into Europe, but in the United States
this species has grown in popularity because of its hardiness. Although
it is not the most colourful of all the butterflyfishes, it makes
up for this by its eagerness to feed on most foods that are offered.
An excellent aquarium fish!
Chaetodon burgessi
Allen & Starck, 1973
Common name
Burgess’ butterflyfish
Natural habitat
On reef drop-offs where there is an abundance of gorgonians
and black coral throughout the Western Pacific from Indonesia and
the Philippines to Palau.
Maximum adult size
5.5 inches (14cm)
Description
The body is white with three broad, brownish-black diagonal
bars. The first of these is the eye bar. A second runs from the
nape to a point just below and behind the pectoral fin. The third
bar runs from the base of the third dorsal spine to the anal fin
leaving the dorsal fin, caudal peduncle and posterior portion of
the anal fin deep brownish-black. The tail is white or translucent
and the dorsal fin has a narrow white margin.
Aquarium suitability
With a bold attitude and a great appetite, Chaetodon burgessi
is probably one of the hardiest butterflyfishes in captivity. It
is not common but soon settles down to aquarium life.
Chaetodon capistratus
Linnaeus, 1758
Common name
Mock-eye butterflyfish, Four-eye
butterflyfish
Natural habitat
Widespread in the Caribbean and the Gulf of Mexico in a
variety of habitats around coral reefs.
Maximum adult size
5 inches (13cm)
Description
A very attractive species with delicate colouration. There
is a dark bar through the eye and a series of thin, chevron-formed
bars along the body. The nape, snout and ventral regions are yellow
and there is a large, white-edged black ocellus forward and above
the caudal peduncle.
Aquarium suitability
Despite some conflicting accounts from other aquarists and
aquarium book authors, this fish is quite easy to keep and hardy
once it is settled down to tank life. All foods that are offered
will be readily accepted
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Marine World Magazine, Frederick Law & Co Ltd., Unit 1, Regal Business Centre, Gorton Road, Manchester, M12 5BX Tel: 0808 129 2939
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