Flatworm predator?
 

Our hammer coral has been receeding for a couple of weeks, previously having been very healthy. Finally took it out and had a look at it, to find 2 large (2cm) planarians. Does anyone know if these are harmless and feeding on necrotic tissue - or did the d**n things cause the problem?
You can find a photo uploaded to the "critters" part of the photo gallery
Thanks for any info

Well I didn't see any flatworms in that pic. If this is one of the typical Flatworms, they will not harm corals IME. They are actually beneficial to the system (eat Algae etc.) it's just that they tend to do very well in some tanks and large colonys form making them pretty much eyesores only.

Had a look at the picture....I think that what you are seeing is remnant pieces of the coral tissue on the skeleton.
Have you checked your water paramaters? i.e. is your calcium level high enough?

Mitch

I had the same problem. Hammer coral, tissue was receding. Had a good look at the coral, saw something moving on it, took the coral out of the tnak, removed 3 big, fleshy coloured flatworms, gave the coral a dip and returned it to the tank.

It grew back out nicely, looked great for 2 months... now it is looking sad and receding again, I think I am going to try the flatworm Xit to see if it helps.

Hey John,
I agree, the flatworm is parasitic. It looks like the coral as camoflague. Remove it ASAP.

Mike

My experience with hammer corals is that they will recede at the slightest irritation.
So if your water params are o.k., and it is a flatworm, the coral is probably retracting because of it, and it should go.
Necrotic tissue on a hammer, IME, will decay and quickly succumb to a brown jelly infection first.

Mitch

Sorry the picture isn't great - but the brown tear-shaped thing that looks like tissue is actually a fairly large flatworm, not the little red/brown ones that explode in numbers. I tried to take a photo after it left the coral, but the autofocus didn't work too well, probably because of the water surface. I have posted it anyway - "gliding away" at least it shows the shape when extended
Water parameters are excellent: sg1.025, nh4 0, no2 0 no3 15ppm alk 3.8meq/l and ca 420ppm
Could be the flatworm is irritating the coral - it irritated me so it had to go.
I'm hoping the tissue recession will stop now.

Thanks again for everyone's input