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My trawl through the latest information from Practical Fishkeeping magazine has yielded something for the marine aquarist ... A Farming Damselfish ...

Yes, you read that correctly.

Stegastes nigricans has been found to be associated with a Polysiphonia alga species on the reef - and furthermore, this alga species is ONLY found where the Damselfish is found!

The scientific paper covering the new find is:

Hata H, Kato M (2006) - A novel obligate cultivation mutualism between damselfish and Polysiphonia algae. Biol Lett. 2006 Dec 22;2(4):593-6.

The Dusky Damselfish, Stegastes nigricans, lives in the wild amid dead Acropora coral branches, where it cultivates algae growing on the dead branches, vigorously defending its 'farms' to the point where divers can find their face masks being attacked by these feisty fishes (!), and it now appears that the fish cultivates a Polysiphonia alga that is never found outside of the 'farms' of Stegastes nigricans ... as the authors say in their paper:

This is the first record of an obligate plant-herbivore cultivation mutualism in a marine ecosystem. Our data also suggest that three other Polysiphonia species are facultatively mutual with, commensal with, or parasitic on other damselfish species.

So, next time you think of Damselfishes as being little more than aquarium ruffians that are only kept by saltwater newbies who don't know any better, think again - there's more to Damselfishes than you think!


Panda Catfish fan and keeper/breeder since Christmas 2002

Neat post, Cali, thanks for sharing. I absolutely love mutualistic behaviors, and this one is one of the coolest I've heard of.

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Critical Fertilator: The Micromanager of Macronutrients

I've heard of damsels killing coral polyps to make algae grow, but nothing quite this extreme. Nice find there.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

I've noticed this behavior while scuba diving in the caymans and there are many species that do it. I later read about it to confirm it. I think it is the coolest thing to hit the dead part of the reef and see the little green and brown patches surrounded by damselfish tending to them.

-Vincent

Apparently more than one Stegastes species has acquired algal cultivation behaviour, but Stegastes nigricans is the most advanced and developed among the Genus in this regard.

EDIT : Just found this courtesy of Google Scholar ...


Panda Catfish fan and keeper/breeder since Christmas 2002