Duncan Coral Polyp Retraction; One Explanation.

[Scrubber_steve]

I once kept a Duncan coral in a tank with water parameters far from what would ever be recommended. But it thrived and I can only assume that these corals should be easy to keep.

However, since attempting to keep a Duncan in water parameters that would be considered perfect I have had one die, and it seemed the specimen I bought recently was going the same way.

Its polyps were extended in the store & during transport. But a short while after placing it in my tank the polyps retracted. And I mean really retracted – sunken in. But I noted that they did extend slightly at night?

I placed the Duncan in a small container of NSW & pop, out came the polyps. After returning it to the aquarium the polyps again fully retracted after a short while.

So I naturally came to the conclusion that something in my water was the problem. And I was correct, but not for the reasons I considered.

I positioned the Duncan in a section of my sump that is gently illuminated by a blue LED, and within an hour the polyps popped. What was in the water that was causing the Duncan’s polyp retraction?

A Vlamingi Tang, a Blue Tang, a Yellow Tang and a Flame Angel!

Very occasionally, one of these occupants was having a quick nip at the Duncan’s polyps, and so it wasn’t easily detected as an issue. I had to be looking at the Duncan just at the right time to see this occurring. And the fact that these fish do not harass another coral made detection that much more unlikely as it wasn't something that would come to mind.

So; for those people out there that are struggling to understand why their Duncan corals polyps are continuously retracted this may be the answer.

 

[jsker]

Interesting observation thank you for sharing

 

[ZoWhat]

Your Flame is an angel and they do nip at new coral. Usually after a week they lose interest bc your prepared food is more of what they want. If the Flame continues to nip you need to research what Flames mostly like and add that to the menu

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Imo the best fish food that every fish goes NUTS for is MUSSEL MEAT. my grocery store sells frozen mussels for $3 a 1 pound frozen container. I thaw, dice up with kitchen knife, refreeze and serve in cubes. All my fish are fataxxes with huge bellies. And go bonkers when the diced mussels hit the tank. lol