Lost another Duncan Coral and cant find out why

ScottyD36 · Oct 9, 2021

So for the life of my I cannot figure out why I cannot keep a duncan coral in my tank succesfully. I have two tanks a 13.5 gallon tank and a 40 gallon tank. My 13.5 gallon tank I had a duncan coral going fine for over a year and a few months ago it just closed up and died. Literally nothing changed parameter wise in my tank. So I bought another duncan coral this time I put it into my 40 gallon tank. It was doing great heads wide open and then after a water change it just closed up and died. My parameters have stayed consitant nothing has changed.
Ammonia - 0
Nitrite - 0
Nitrate - 15ppm
Phosphate - .11
Salinity - 1.025
PH - 8
Alkalinity - 10.2
Calcium - 439ppm

I am at a complete loss. I have Acans, Zoa, Favia, Blastos which are all completely fine no problem at all. I am just at a loss here and trying to make sense of all of it. If anyone has any idea what could be going on. I do have two clown fish that I am thinking maybe tried to host it and maybe that upset it but I dont think that would make it close up over night and just die.

lapin · Oct 9, 2021

Are your tanks connected?
Im thinking it might be some sort of bacterial problem or parisite that only effects duncans.

ScottyD36 · Oct 9, 2021

lapin said:
Are your tanks connected?
Im thinking it might be some sort of bacterial problem or parisite that only effects duncans.

Two separate tanks. That’s why it’s so confusing to me.

JGT · Oct 9, 2021

Do you use RODI H2O?

Darren in Tacoma · Oct 9, 2021

Sometimes it is just a mystery.

Lavey29 · Oct 9, 2021

I have the same problem with goniopora. Everything else is fine but can't seem to keep those going. Duncan's seem to be very hardy. I've tried them in 4 different spots in my tank with great success so I'm guessing you have a parasite or bacteria in your water which may be feeding off them. This may be going on slowly unknown to you and then a slight change in parameters during a water change puts it into shock and collapse.

I'm only speculating of course but if everything else is good and the Duncan was fine for a period of time then perhaps something is slowly damaging it internally.

Miami Reef · Oct 9, 2021

ScottyD36 said:
It was doing great heads wide open and then after a water change it just closed up and died.

This is the clue! If it was me I’d send out an ICP test.

Lavey29 · Oct 9, 2021

Was there any other coral near them that may have stung them?

workhz · Oct 9, 2021

Not super helpful to you but I just moved my Duncan to the bottom of my tank last week and it closed up for 3 days. I moved it right back to its old spot on a frag rack and bam ... open in 5-6 hours.

Lavey29 · Oct 9, 2021

workhz said:
Not super helpful to you but I just moved my Duncan to the bottom of my tank last week and it closed up for 3 days. I moved it right back to its old spot on a frag rack and bam ... open in 5-6 hours.

I keep mine on the bottom in the back corners pinched in between rocks. Low light and flow. They closed up like tight sticks at night but open all day

vetteguy53081 · Oct 9, 2021

Moderate light and water flow. Look very closely at stems and see if you see grey or black bugs crawling around.
What is current Phosphate reading and are you feeding them? If unsure about bugs, simply give them a dip.
I would suggest placing your Duncan coral either in the lower part of the tank or straight in the middle. The sweetest spot is the place out of high water flow with moderate distance from T5, metal halides, or LEDs. Additionally, water plays an importance with them and consists of several major factors which are calcium, alkalinity, temperature, flow, and pH.