Chaetodon mertensii
| Latin name | Chaetodon mertensii - Cuvier, 1831 |
|---|---|
| Local name | Seychelles butterflyfish |
| Family | Chaetodontidae - Chaetodon |
| Origin | East Indian Ocean, West Indian Ocean, Australia, The Red Sea, Indonesia |
| Max length | 13 cm (5.1") |
| Minimum volume |
300 l (79 gal) 
|
|---|---|
| Hardiness |
Hardy
|
| Suitable for aquarium |
Suitable with care
|
| Reef safe |
Not reef safe
|
| Aggressiveness | Mostly peaceful but might be aggressive towards similar species |
| Recommended |
Macroalgea (Eg. seaweed / nori) Microalgea (Eg. spirulina) Small crustaceans (Krill, mysis, artemia...) Zooplankton (Cyclops, pods...) |
|---|---|
| Mostly |
Large polyp stone coral (LPS) Small polyp stone coral (SPS) Soft coral |
This species likes to eat tubeworms.
This species sometimes nibbles at clams including Tridacna species.
This species is not neccessarily aggresive, but it has a greater tendency towards aggresion then other species of the same genus.
This species must be fed with an appropriately varied diet.
These fish flourish better without other members of the same species in the aquarium.
This fish requires feeding several times a day, especially when newly added.
When the fish can find its natural food in the aquarium it requires less frequent feeding.
These fish should be kept in a well run aquarium where they can "graze" algae from rocks and stones.
If there are insufficient algae on the rocks, it is important to feed more frequently and supplement with algae rich food e.g. Spirulina.
This species needs good hiding places, for example, between live rocks.
This species revels in swimming and requires an aquarium with ample space.
This species is very shy and docile, so one should be careful when keeping it with more aggressive fish.
This species eats glass anemones (Aiptasia).
But occasionally one finds an individual fish which refuses to eat them.
This species belongs to what is known as Xanthurus complex, which consists of three species which resemble each other.
Chaetodon mertensii and Chaetodon madagaskariensis
These two species are very similar and is considered to be one species by some.
They are distinguished by the larger orange area than of C. Xanturus.
Chaetodon paucifascatious
This species is recognized by the area which in the other two is orange, here is reddish.
Chaetodon xanturus
Here the orange area is smaller than C. mertensii and is more moon shaped.
Some species of the Chaetodon genus are grouped together in what is known as a "complex", since they are so very similar.
Regardless of resemblance, it is important to be able to distinguish them, as in some cases they vary greatly in their needs. Sometimes there are just small differences in colour or pattern, but in other instances it is vital to know where the fish originally come from.
The Butterflyfish are known for their attractive patterns and colours. They are closely related to Angelfishs, but can always be distinguished, as they lack the spines on each side of the head of the Angelfish.
A smaller group of these fish will seek out primairily soft corals, like Zoanthus. A larger part of the species will target different types of LPS corals. Butterflyfish are also known to seek out anemones, tubeworms and bristleworms.
Therefore it is important to choose the correct species in relation to the corals wanted, if one desires to keep Butterflyfish in a coral-aquarium.
Bristleworms, tubeworms and other small invertebrates are also a part of the diet for many Butterflyfish.
It can be problematic, with many of these species, to get them eating in the beginning, but many of the species cannot resist live zooplankton or live mussels with crushed shells. Another option is to mimic their natural behaviour by stuffing their food into coral skeletons or stones.
They ignore most other fish and are generally peaceful, therefore multiple Butterflyfish will have no problem living together. One should however be cautious about keeping similar species together unless they are a couple.
As these fish can be difficult to acclimatize and get feeding, it is important to buy healthy fish, to avoid having to deal with more problems. Make sure to check that they do not have parasites or any visible infections.
There are some species that should not be kept in an a aquarium, as they are food specialists and will almost always refuse to eat replacement foods. It can be possible to breed some species, which will eat frozen foods. Otherwise the only way to keep food specialists is by feeding them their natural diet, which consists of live SPS or LPS corals for example.
| Aquarium trade | Yes |
|---|---|
| Distribution | Pacific Ocean: Ryukyu Islands to the Philippines and extending to Lord Howe, Rapa and Tuamoto islands. Replaced by Chaetodon madagascariensis in the Indian Ocean, Chaetodon xanthurus in southeast Asia, and Chaetodon paucifasciatus i |
| English common names |
Merten's coralfish Merten's butterflyfish Mertens' butterflyfish Atoll butterflyfish |
| Danish common names |
Atol-fanefisk |
Bob Fenner. Corallivorous Butterflyfishes… For Aquariums? - Wet Web Media - (English)
Scott W. Michael. 2004. Angelfishes and Butterflyfishes (Reef Fishes Series Book 3) TFH Publications / Microcosm Ltd. - (English)
Bob Fenner. Butterflyfishes; Separating the Good Ones and Those You Don't Want - Wet Web Media - (English)
Collection of links to additional information - Wet Web Media - (English)
Tea Yi Kai. 2014. Reef Nuggets 2: Aquatic Lepidopterans for your reef (Revised edition) - Reef Builders - (English)