Gigas possible pinched mantal

[BradB]

Today I noticed my gigas mantle not extending in the upper right portion of this picture. Should I freshwater dip? Wait and see?

 

[OrionN]

It is the star polyps that stinging it. I would clear all the corals from the shell and keep them from stinging his mantle.

 

[BradB]

Those are clove polyps, they don't have nematocysts, but I've considered (and even posted about) removing them. They've been on the clam for over a year and today is the first day I noticed the mantle retracted. Removing the clove polyps by scraping, probably with a wire brush could be more irritating to the clam than leaving them. A freshwater dip might be a good opportunity to try.

 

[OrionN]

PMD does not just come on new in the tank. You got to add a sick clam (with PMD) to the tank before you get it. That mantle is irritated by the coral. All coral has way to fight for tuff. It is most likely the coral irritated the mantle of your calm.

 

[minus9]

PMD does not just come on new in the tank. You got to add a sick clam (with PMD) to the tank before you get it. That mantle is irritated by the coral. All coral has way to fight for tuff. It is most likely the coral irritated the mantle of your calm.

This^^^^ Also, you can safely pull the clam and scrape off the coral without issue. As @OrionN mentioned, PMD doesn't just show up without being introduced, most likely from another clam. All corals have a defense mechanism, some are chemical, which may cause other issues. If the mantle is retracting, then most likely something is irritating it. Check for hydroids, aiptasia, etc..

 

[BradB]

This clam was added 3 1/2 years ago, after another clam died in a 400 gallon system that has been set up for years. Could the protozoan have lived in the tank that long? Could it have been introduced on a coral frag?

What is the risk to a 30 minute freshwater dip? Even if it probably won't do anything, I'd rather try it if it is more likely to help than hurt.

I removed the cloves around the pinched area. Today it is still pinched, with cloves touching the mantle everywhere except where it is pinched. If the cloves were at fault, wouldn't I see the mantle pulled back in other parts? Wouldn't it recover now? It is not so easy to "safely pull and scrape" a clam too big for a 5 gallon bucket. Removing most of the cloves is not so hard, but they will grow back if even a tiny thread is left. This makes the freshwater dip idea more appealing, which might kill the cloves after aggressive scraping.

Aiptasia won't survive in my display, I have an emperor angelfish that eats them. I worry he might nip the clam, but I don't see him doing it, and the damage is all in one spot. A hydroid or something else might be at fault, but I am scared to stick a finger in and poke around.

 

[minus9]

Just give it a day or two. My clams will retract the mantle is spots, then they're back to normal the next day or two. It's when the mantle starts to retract more and more that you should worry. Also, these clams are completely exposed to open air during low tide, so pulling it out shouldn't be an issue. You can place it in a tub with some tank water, but it doesn't have to be submerged, just enough water to help rinse away the stuff you're removing from the shell. I don't think you need to do a freshwater dip just yet. I would give it a day or two and see what's going on. PMD is something completely different than just part of the mantle retracting.

 

[BradB]

I have a Europe trip planned this summer. Losing the clam while I am away could wipe out the tank, especially if the house sitter tries to do something despite being told not to.

Exposure to air is not my concern. These clams are not handled in the wild, do not like being jostled around, and there is always a chance of dropping it. This thing has to weigh a lot, and I have to bend over to lift it out. They squirt water too.

 

[OrionN]

I think light scraping to keep the polyps in check until you get home again would be the thing to do. Have fun on your trip.

 

[BradB]

Saturday I did a 10 minute freshwater dip and removed the coral from the shell. There is still no change.

I notice slight white/bleaching around the edge of the mantle, but not where the mantle is pinched. This is so subtle I doubt I could even photograph it, and it is probably nothing, but I thought I'd mention it. This is not new, you can even see it in the picture I posted if you know where to look, but I didn't notice it before the dip.

I did try running my finger around the inside shell in the pinched area, and felt nothing but smooth shell.