Help, Clams have a 3rd Hole.


New member
Hello all,

A few of my clams developed a third hole. It is located in between the incurrent syphon and excurrent syphon in the middle mantle.

The Clams are still opening and extending their mantle. The central mantle is not bleached either.

I'm also sure that it is not a fish bite.

Any advice would be appreciated.

Wow! Thats strange, It looks like a tear of some kind to me. Like maybe a snail or something fell on it while it was open?
I've never heard or seen that happen before. Do you have a fish with a bit radius that would be about that big?

How long has the hole been there? Your clam looks like it's doing well regardless.

If you figure it out, let us know.

Clam hole

Clam hole

A crocea clam I received this past Friday has the same "feature" (came from a wholesaler in Toronto area I believe). Clam is slightly less than 2 inches in size. So I would like to know what it's all about as well. I.E. is it in fact a problem?
What are your water redaings? Calcium, ph, alk, salinity, ammonia, nitrite, nitrate?

How do you suppliment calcium, into your sustem?

Size of tank, kind of lights?

More info may help.



Have you had these clams for awhile or are they recent additions? I ordered a clam once thorugh MO, and when it got here it had a hole exactly like the one you have pictured there. It healed up within a week. How long has the clam been like this for, and is this only happening to one of them or are there others?
A while ago I was using thick kalkwasser paste to kill aiptasia and somehow managed to get a couple blobs on one of my clams. I didn't realize it at the time but a short time later when I noticed two holes in the center mantle area I knew how they got there. I don't know if this is the case with your clams or not but it is one way it can happen.
clams with 3rd hole

clams with 3rd hole

Just a little bit of background about the tank.

150 gallons total volume.
lighting consist of 2 -400W iwasaki and 7 VHO actinic.
Haven't added any clams lately.(last 6 months). MH on for 8hrs and VHO for 10hrs.

Water parameters:
Salinity- 1.025
Nitrate- 10 ppm ( Adding Sodium Nitrate every week )
Calcium- 425 - 450 mg/l (Using Reef Advantage as part of 2 part solution)
Alkalinity - 2.5 - 4.5 meq/l (Using Baking Soda as the second part of the 2 part solution).
Amonium/Nitrite - ZERO.
Water temp. - 78- 82f

Change 20gallons of water every 2 week. Replace 1/2 cup of Carbon every 2 weeks.

Don't recall on doing anything new on the regular routine.

Have about 30+ clams in various sizes. 7 Clams are affected with the 3rd hole issue.

Thanks for all your help,