Crocea clam bleaching?

[catmel]

Any ideas as to what could cause a crocea clam to bleach? I got a small one ( about 3-4 inches) from a local frag swap a few months ago. When I first got it, it was a nice black with some blue.. now its almost completely white.. though it seems to be opening up ok.

I have it sitting on a rock near the top of the tank. I knew they like high light and to be on rocks with low-medium flow.

My lights are 2 x 150 watt MH and 2 x 96 watt PC ( one is 50/50 one is actinic) temp about 79-80 ( gets to 82 sometimes during the day over a peroid of several hours) calcium 400-420, alk 8, mag 1400, ammonia /nitrate/ nitrite 0

The only thing i can think of, late sept the tank got a bit warm since we had a heat spell here, ( tank was 86) and I had to add some cooler water ( in the sump) to cool it down. I also did run some phosban for a day .. it seemed bleaching has started after that.. but, the tank has been stable, no more phosban.. why is it still bleaching? is it getting too much light? ( I know they require very high lighting, however.. is this possible?) any help would be great.. I'm worried this little clam isnt going to make it. I'm a bit bummed.. I waited for several years and did lots of research before buying one.. blah!

Thanks in advance

 

[mr_X]

The temp fluctuation is not a good thing, but i would look at your lighting. 150 watt halides isn't much over a 75 in my experience. If the bleaching has been gradual, i would not think a single temp spike to be the cause.
Have you tried running a fan across the surface of the sump to cool it?

 

[leftyfish]

Here is a good article on clams, Feature Article: A Look at "Mysterious Clam Deaths" — Advanced Aquarist | Aquarist Magazine and Blog

 

[catmel]

The temp fluctuation is not a good thing, but i would look at your lighting. 150 watt halides isn't much over a 75 in my experience. If the bleaching has been gradual, i would not think a single temp spike to be the cause.
Have you tried running a fan across the surface of the sump to cool it?

Yes, the bleaching has been gradual. It started out as a few white spots here and there, now its almost completely white. It seems open and does react to waving a hand over it ( over the top of the water ) by retracting

Temp in the tank has been stable since then, its just the one spike I had. It stays around 80. for the most part. I do notice when my husband has the heat on in the kitchen it can get up to close 82, but thats very rarely.. I do use a fan to cool the water when I can

I have 2 x 150 MHs and 2 x 96 watt PCs, so its about 492 watts total over 75 gallons.. I would think this would be enough? PCsare on from 9:30am - 8:30pm, MHs from about 11:30am-6:30pm

I had gotten it from a frag swap, perhaps it was in a not so highly lit place, and putting it in my tank directly under MHS ( high in the tank) may be causing bleaching? If thats possible, not sure what to do, since its attached itself to the rock

 

[mr_X]

Watts per gallon isn't really a good gauge to go by. Those power compacts aren't doing a whole lot IMO. Halides span about a 24" space, so you are only looking at 150 watts of metal halide every 2 feet of tank. I used a PAR meter on a few different 150 watt lamps and fixtures a while back and they put out some weak numbers. Over 15" of water, a 150 watt pendant was only reading 50 on the sand bed. Not a ton of light IMO.
The only way to know for sure if it's a lighting issue or not is to check the output with a PAR meter.
Did you immediately put it up top, or work it up from the sand bed over a short acclimation period?

 

[catmel]

I put it directly at the top of the tank, the person I had got it from said they do well with high lighting ( which I had read previously) and to put it right at the top. Maybe this is what caused the bleaching?

would it be safe to try and remove it and put it lower? If so how would I go about that? Its attached to a large rock I cant move lower in the tank

 

[mr_X]

Clams are found in shallow waters, where light is most intense. It's correct that they require a lot of light, but i suppose you could move it down a little to see what happens, but I'm thinking up is the way....
Do not attempt to pry or cut it away from the rock. That could kill it. if anything, you'll have to chip the rock away under it to free it up.

 

[crister13]

I have my crocea clam on the sandbed and hes doing fantastic. I have an 8 bulb T5 fixture and hes 28" down.

 

[mr_X]

That 8 bulb T5 fixture is putting out a tremendous amount of PAR. The 150 watt halides are not.

 

[catmel]

Interesting.. thanks!

 

[crister13]

O ya................... lol. GL with your clam!!!!!!!!!!!!!!!!!!!!!!!!