Acan is receding / dying

[Fishingandreefing]

I acquired another mini acan colony. It was doing great for a few months but then suddenly went down hill. It’s a sps dominated matured tank. It’s sitting on the bottom getting about 80 par and low flow.

I do feed the tank with reef energy.

alk usually drop to 6-7 (my sps are sucking up all the alk and cal I think. Dosing kalk with ato and adjust it with 2 parts. I am keeping it at around 8.3-5)

nitrate .11
Phosphate .10
mag 1350 (bumping to 1400-1430)
Cal should be around 450
salintiy 10.25/26

most of lps are doing ok and sps are growing.

I am running a bit of rox .08 carbon and gfo (about 35% recommended dose)

any help be greatly appreciated.

 

[CoralB]

Inspect for critters and are you feeding it manually ? Also my experience is mine always did better in diffused light .but my guess is critters of some kind also could you elaborate on the statement of “most lps doing ok “ ??? Which ones are not and what do they look like ? Pics are helpful

 

[Fishingandreefing]

Inspect for critters and are you feeding it manually ? Also my experience is mine always did better in diffused light .but my guess is critters of some kind also could you elaborate on the statement of “most lps doing ok “ ??? Which ones are not and what do they look like ? Pics are helpful

Prob fed about once a week. I dipped it with lugol iodine after didn’t do well. Not sure what critter would causing it.

 

[Biokabe]

Well, what do you have in your tank? Quite a few things consider acans to be tasty treats.

 

[Fishingandreefing]

Well, what do you have in your tank? Quite a few things consider acans to be tasty treats.

Tangs but why would they nip only the bottom?

 

[Biokabe]

Tangs but why would they nip only the bottom?

All you have in your tank is tangs? No snails, no crabs, no other fish? No flatworms or shrimp or nudis or anything else? Are there any nearby corals that could be stinging it? Any corals that could be engaging in chemical warfare?

If you want help, we really need a lot more information than what you've given us to figure out what's going on.

 

[Fishingandreefing]

All you have in your tank is tangs? No snails, no crabs, no other fish? No flatworms or shrimp or nudis or anything else? Are there any nearby corals that could be stinging it? Any corals that could be engaging in chemical warfare?

If you want help, we really need a lot more information than what you've given us to figure out what's going on.

No visible flatworms but don’t think that would eat the acan. I got nassarius snails and no shrimps. The corals are not close to it. The favia shown in the picture has tentacles that are very short. I moved it to a lower light area shown in the picture. That empty space in the front was where it used to sit at

 

[Fishingandreefing]

My nitrate is at around 10 and my friend suspected that it has to do with it. Anyone?

 

[JGT]

Thinking that they are dying and receding or CUC is eating the dead flesh. They all seem to be towards the bottom where they wouldn’t get much light.
Don’t think 10 nitrates is a problem.

 

[Fishingandreefing]

Thinking that they are dying and receding or CUC is eating the dead flesh. They all seem to be towards the bottom where they wouldn’t get much light.
Don’t think 10 nitrates is a problem.

Yup I got no clue

 

[Biokabe]

10 nitrates definitely wouldn't be a problem. Acans love moderate nitrates - 10-20 is just fine for them. Higher would probably be fine too. I don't think they're really lacking nitrates though - coloration looks strong.

Without any obvious predation issues, it's hard to say for sure. Certain crustaceans will predate acans, but you don't really have any. Angels, filefish, triggers, parrots, and butterflies will sometimes feast on them, but again, not really present unless you just forgot to mention them.

Those remaining polyps look nice and fleshy, so unless you've recently changed feeding habits drastically, I don't think lack of nutrition is a problem. Which brings it to one of four potential causes:

1) Physical placement. I know acans are often touted as liking lower light and lower flow, but I've found in my own tanks that they aren't as allergic to higher light levels as some LPS corals are. I've also found that too-high flow can be detrimental to them, and I've finally found that they sometimes don't appreciate being in the sand. So those are the physical things I can think of: either it's not getting enough light, it was getting too much flow, or it wasn't liking the sand. Of those, I think the sand is the likeliest culprit; you've got some gorgeous and healthy euphyllia in there, and I don't think they'd be doing so well if your flow through the lowest level was too high.

2) Unknown predator. Maybe you have a hitchhiker or a tiny predator that you're not aware of that's just loving that acan. I don't think this is terribly likely, but it is a possibility.

3) Coral warfare. There are a number of corals that could cause an issue with any other coral. There's a lovely toadstool (chemical warfare). Possibly some nephthea/sinularia (picture is too zoomed out, so I can't tell if some of those corals are finger leathers or some species of SPS... if there are leathers, that's another chemical warfare vector). But most pertinent is the war coral that's right next to where you used to have those acans, and is still pretty close. I know the tentacles you usually see aren't very long, but they can put out sweepers that can be significantly longer. Sweeper damage often presents in the same format as what you're seeing.

4) Random disease. Also not something I think is terribly likely, but it's possible your coral picked up a disease and is slowly succumbing. The only real thing you can do is feed the coral heavier and hope that you can strengthen it enough to beat it.