Duncan coral turning green?

[abby_n]

Hi, I started my first saltwater tank this summer and have a lot of questions. I have a 32 gallon bio cube. It has been running for a couple of months and I’ve been filling it up with corals lately. So far I have a variety of coral, two emerald crabs, four snails, and a feather duster worm. I’m hoping to keep it as an invert only tank, but let me know if that sounds like a bad idea.

One of the first corals I got was a Duncan. For the first couple of weeks that I had him he was kind of white/tan with a little more coloration near the tentacles. Recently, it has started to turn fluorescent green on both the trunk and the polyp. It’s behavior hasn’t changed at all.

A couple thoughts: the color looks almost the same as the reef energy plus coral nutrition food that I have put in the tank a couple of times, could that have any thing to do with it? Also, I have already made a few mistakes and unfortunately have been away from the tank for up to two weeks at a time because of work. I am most curious to know if this could be a stress response as I have heard of corals fluorescing when they are stressed.

Has anyone heard of this coral becoming tinged with a fluorescent green color? I feel like I may be missing something obvious. I’m eager to learn more and would love to hear what you all think.

[Sniperhank]

This is what duncans will do. My main colony has changed its color as it has been moved into different tanks each time. Currently of its ~100 heads, they also aren't the same color and change along with the tank moves.
A side note will be that these photosynthetic corals do not need to be fed. In a small tank such as yours, these commercial foods will quickly gunk up your water with phosphates and break it out in algae if not a crash at times. I would suggest not feeding at all.

[bribo12]

As long as it is not receding and open I wouldn’t worry.
On a side note I’d add a couple small fish. Fish waste = coral food!

[abby_n]

Originally Posted by Sniperhank

This is what duncans will do. My main colony has changed its color as it has been moved into different tanks each time. Currently of its ~100 heads, they also aren't the same color and change along with the tank moves.

A side note will be that these photosynthetic corals do not need to be fed. In a small tank such as yours, these commercial foods will quickly gunk up your water with phosphates and break it out in algae if not a crash at times. I would suggest not feeding at all.

Wow okay that is cool. Do you have any idea why they do that? And thank you for the feeding tip. I have two kinds of food and have only fed I think three times total over the past two or three months. You don’t feed yours at all? And is it the nitrogen cycle I should have been watching to tell if it is harming the water?

Thanks!

[abby_n]

Originally Posted by bribo12

As long as it is not receding and open I wouldn’t worry.
On a side note I’d add a couple small fish. Fish waste = coral food!

Good to hear! I’ll keep the fish tip in mind, thank you.

[Sniperhank]

Originally Posted by abby_n

Wow okay that is cool. Do you have any idea why they do that? And thank you for the feeding tip. I have two kinds of food and have only fed I think three times total over the past two or three months. You don’t feed yours at all? And is it the nitrogen cycle I should have been watching to tell if it is harming the water?

Thanks!

No, I don't feed at all. The photosynthetic corals in our tanks can thrive on having proper lighting alone.

In terms of the water from using liquid coral foods, they are packed full of phosphates. They build up quickly, and most tests are junk for such or hard to use, so these levels can easily build up. This is especially true in smaller tanks. So in general, a good rule of thumb is to just not target feed corals unless you keep non photosynthetic corals and have outstanding filtration and water change schedule.