What's going on with my Derasa? (Mantle receding)

[FalsePerc]

Hi all,

I've had this Derasa clam since it was about 4", now she is almost 7" but her recent behavior has been concerning to me. The mantle has gradually, over the course of 4-5 weeks, been receding such that the inside of the clam shell is no longer covered by mantle tissue. It started on one corner and seemed to hold there for a long time. Within the past few days, the full mantle has become affected. The only thing I can think of is that I purchased a coral beauty angelfish prior to anything happening to the clam. Could the angel be nipping at the mantle?

Params are as follows:

Temp 80.7 F
Salinity 1.025
pH 8.0
KH 10.6 dKH
Ca2+ 405 ppm
Mg2+ 1040 ppm
Phosphate 0.25 ppm
Nitrite 0ppm
Nitrate <20 ppm

Picture is attached. What can I do to save my derasa clam?

Thank you

Mike

 

[FalsePerc]

Tank is 65g w/ 20g sump lit by a Radion LED fixture that is a mix of blues in the morning and evening, and "full blast" lighting for 4 hours (30% random cloud cover) every day.

 

[Stevenliu9]

It is entirely possible something is bothering the clam. My 9" derasa was closing up all the time for a while, turns out a rabbit fish has been nipping it. I moved it to another tank and now its happy again

 

[falconut]

I'd say it's the new angel. I have a 7" Derasa, that I had since 3". It was doing awesome, then within a month after adding a Lamarck angel, it starting looking like yours. I managed to catch the angel and the clam has been opening fully since. I think I saw the angel do a small nip once in the hour I was watching.

 

[moliken]

that is a serious issue. angels and clams rarely mix well. sorry.

 

[Stevenliu9]

Angels can be a miss or hit, I've kept many angels and clams together in the past and presently have a flame angel and a watanabe in, and neither bother the 3 clams I have (knock on wood). But my previous flame angel nibbled on clam mantle quite a bit and I had to remove him.