Green Duncan Question

brandong

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I’m noticing mine has much shorter, thicker tentacles compared to most of the Duncans I see online, which usually have long, flowy tentacles. Mine stays really puffy with chunky tips instead of stretching out.

The coral looks healthy and opens fully every day, good color, and it eats when I feed it. Tank is around 3 months old.

Here’s a pic of mine vs. what I normally see online:

20251118_214013_DE1EAAAE-60BA-40E0-BEAA-DB0CA80B9998.png

20251118_214013_92D1F761-EB3B-4B52-9F68-8BBE60E3FE25.png
 

Renfield42

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What kind of flow is it seeing?

Mine enjoys fairly strong, varying flow. The tentacles are constantly in motion, but not whipping.

Does it change its appearance if you turn the flow off?

Check to see if your alk is 8 or so. If you have to adjust alk, do so slowly. Rapid changes in alk will stress corals or even kill them.

I also noticed quite a bit more extension after I started dosing Red Sea AB+ (aminos) even though it was getting fed regularly. (All of my LPS and zoas reacted positively)

It’s eating and opening regularly so it sounds like it just needs some tweaks to its environment.

If the tank is still settling in and parameters are still varying that tends to make most corals less happy in general.

How long has the Duncan been in the tank?
 
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Naekuh

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Duncan's will poof up and extend really long dependent on water salinity.
They will also tell you if they are not happy or if the water sucks.
 
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brandong

brandong

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Duncan's will poof up and extend really long dependent on water salinity.
They will also tell you if they are not happy or if the water sucks.
Alkalinity - 8.7
Magnesium - 1390
Calcium - 577
phosphates - 0.35
Nitrate - 8.5
Ammonia - 0.0
 

Coral Memere

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Flow and light. Duncan's like light and yours may be too far away, near the bottom like that. They extend tentacles to grab things out of the water column... So may sure the water is swirling past them. Tour pic makes it look dim and protected. Throw her up top, out the window in her hair and watch her strut her stuff!!
 

Naekuh

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How long has the duncan be in?
It can be acclimating... and how often you feeding it?
Again it can just not be happy because its in a new enviorment, and can take several weeks if not a month to extend like that.

Infact my large colony of over 50 heads, still looks like yours sometimes on some days.
 

Mr. Mojo Rising

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I agree light and flow for duncans. Even in the LFS pictures the tentacles are clearly moving with the flow. I put them about halfway up the rockwork with medium light and flow. Are the tentacles swaying in the flow in your tank?
 
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brandong

brandong

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I agree light and flow for duncans. Even in the LFS pictures the tentacles are clearly moving with the flow. I put them about halfway up the rockwork with medium light and flow. Are the tentacles swaying in the flow in your tank?
it is getting plenty of flow where it was at, i’ve read they like low flow though so I’m debating moving it a few inches.
 

GHOSTLY

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Ill send a Pic later, my 7 duncans have some weird behaviors. During the day they're shorter and thicker. During feeding time they're skinny and long. Ive got them in around 150 pair and pretty low flow where they just sway side to side
 

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