Possible Hammer Pest

kase1084 · Nov 22, 2025

Hi Reefers,

I’ve been struggling with a sick hammer coral for a while which has gradually been receding and shrinking away from its skeleton. I recently had a torch do the same thing near to where the Hammer is, but it died while I was overseas and I came home to a completely bare skeleton and a minor ammonia spike.

These are my current values
Alk 9.4dkh
Calcium 500 (I’ve temporarily turned off the calcium dosing channel).
Phosphate 0.09
Nitrate 11
Mag 1390
Temp 25.5 (degrees Celsius)
Salinity 35ppm

I have moved it to low flow. I have dimmed the lights (2 x Red Sea ReefLED 115s at 15700k), and I’m not sure where it’s still sulking.

I have now I have tried a 15 second freshwater dip in RO water to try to dislodge any beasties that might be munching on it. There were some “things” I shook loose which might have been just dead tissue or might have been euphyllia munching nudibranches, or perhaps something else? There are black …. perhaps…. munch holes… on the tips of some of my polyps?

The hammer is now very retracted following the FW dip, should I still feed it tonight?

These are my photos of the “things” which may or may not be pests, and also the suspected “Munch marks”.

Mr. Mojo Rising · Nov 22, 2025

You should not feed a stressed out coral, when corals are stressed or sick just like us they lose their appetites. Personally I'm against freshwater dips for corals, you can easily kill or damage corals by doing this, especially when they are already stressed. Touching it further stresses it. The best thing you can do is put it down somewhere and leave it alone. I would also suggest not dim the lights, because that affects every coral in the tank. Lights are a set it and forget it kind of thing. If a coral needs lower light it should be moved to a position of lower light. Good luck with that!

Tikki · Nov 22, 2025

Can’t tell much about the brown thing on your finger, might just be detritus. I think if it were me, I would do an iodine based dip and try a different location in the tank where you can observe well. I would make sure nothing’s settling on it and not try feeding it. You may end up with infection. How long has it been in the system and how long has it been declining? What’s flow like? Sometimes a nice size water change and some fresh carbon can help perk things up.