The Maldivian clown fish, in Dhivehi Maagandu mas, taught me the American way of symbiosis, and a fascinating fact about their relationship with anemones.
There are 29 Amphiprion species in the subfamily Amphiprioninae. In similarity to hermit crabs, there’s one black sheep in the (sub) family. That’s Premnas biaculeatus, the spine-cheeked anemonefish or maroon clownfish – with it’s very own genus.
Clownfish belong to the same family as the damsel fishes, the Pomacentridae. There’s eleven times more damsels than clowns in the waters. Damsels have a very similar body shape to clownfish, but instead of red hues you find them in blue, yellow, black and white combinations. The name damsel fish might have to do with their defense behaviour. Like a damsel in distress, they seem a bit desperate to chase you away. To do so, they actively swim into your face. Their faces somehow support the impression that they are constantly stressed.
The ID of a clownfish in the Maldives is surprisingly simple. It is said that only two species live in the Maldives, that’s A. clarckii, and A. nigripes. I wonder if that’s true at all. It seems a bit too simple. But it’s a blessing if it’s true, because there are many similar looking species. Especially the pink clownfish, A. perideraion, looks much like the Maldivian clownfish.
The species was redescribed in 1971, from Funidu Island (aka Funadu or Feydhoofinolhu), South Male Atoll, Maldives. ‘A redescription of Amphiprion nigripes Regan, a valid species of anemonefish (family Pomacentridae) from the Indian Ocean.’
For the original description only one specimen was taken, and the location was poorly defined as ‘Maldives’ (page 230). Charles Tate Regan, a British ichthyologist described more than 200 species of fish, and our clownfish was one of them in 1908.
In the Maldives you often see both species of clownfish together in one anemone, and I find that remarkable. There isn’t much space in an anemone, and wouldn’t usually two species compete for safe space? There’s also often the domino damsel ⁹Dascyllus trimaculatus) around. But there’s more to it.
It is well known that clownfishes, or anemone fishes life in anemones, and both protect each other. We would usually just call this symbiosis. And that’s confusing and has been confused a lot. Since both animals benefit from their co-existence, we would call their symbiosis mutual. If only one would benefit, and the other wasn’t bothered at all, it would be called commensalistic symbiosis. Parasitic symbiosis is a form of symbiosis where one is harmed to the benefit of the other. There are more terms for other combinations of course. But, I learned this is the American way.
In Europe it seems to be established, that only mutualistic symbiosis is called symbiosis. Symbiosis is always to the benefit of both in that way. The other forms of long term interactions between different species would be commensalism, parasitism and so on. In the end it’s just language, and details get lost or confused in translation.
You would use differential equations to study the level of symbiosis. But we don’t do math here, we have another fact that I find interesting:
The Maldivian clownfish is remarkably loyal. It is exclusively magnificent. According to the book ‘Fautin, D.G. and G.R. Allen, 1992. Field guide to anemonefishes and their host sea anemones’, which is the source for fishbase in this case, lives A. nigripes only together with the magnificent anemone, Heteractis magnifica. From my own observations I can confirm this. I never found one in a different anemone.
This huge anemone does not display this high fidelity in return. At least twelve fish species, not only clownfish, are known to live in symbiosis with H. magnifica. It can well be that domino damsel, A.nigripes and A. clarckii share one H. magnifica.
So if not the anemones, are all clownfish loyal at least? They are not. Just a handful are.
A. clarckii can be found in ten different anemones, of which two have only A. clarckii as partner. So there’s both, loyal clownfish and loyal anemones.
A search in the internet confirmed this information, I couldn’t find a photo of A. nigripes in anything other than H. magnifica.
So some anemones host only one species of fish, some Amphiprion species live only in certain anemones, but most of both groups have several species to choose from. And whatever combination you find, it is always a magnificent moment and a great photo!
English 
Deutsch