Pale spots on derasa

[keri]

Hi all
Was wondering if anyone knows what these pale spots on my clam could be? You can see them as whiter dots in the picture, they don't look as if there is any fungus or growths of anysort, just areas that lack pigmentation. They have been there since I got the clam (over a month I think - I'll have to look) and don't seem to be affecting growth at all as there is a new ridge of growth about 1/6" wide. I'm getting over a recent bout of dinoflagellates so the tank ias a little stressed but really tho dots have been there since day 1. (or maybe even at the store, I'm not sure) Could it still be stress? He's on the rocks because that's where I *thought* he should be placed and by the time I realized otherwise he was allready firmly attached.
Thanks!
edit: he looks a little shrivelly because lights were out for about 10 mins when I took the pic - my camera is acting up and doesn't like the T5's.

 

[candycane]

Dinoflagellates and symbiotic zooxanthellae are pretty closely related.
Also the Derasa has a number of issues and I would have a couple of ??? (if you don't mind).
It doesn't look like there is anything picking at it, but if it is attached and it has a rock smashed up against it's shell (or is that something else on it's right?) it probably can't open all the way.
I would say a protozoan like WhiteSpot Disease, but it doesn't appear to be attacking the flesh of the clam or eating away at it. Usually WhiteSpot Disease is also much smaller.
I would look at Centralized Bleaching as an underline cause right now. if the clam was in to much illumination, and moved to another tank with too much illumination - it would caused Centralized Bleaching. So would tank temps that are to high though.
Is it up higher on the rocks and are you using a lot of t-5 lighting and is it just T-5 lighting? When you purchased the clam, was it mainly in the center of the mantle where the siphons are and then started to develope the spots later on? Or have you not owned the clam that long? What do you keep your tank at for specific gravity and how did you treat the dino? Also water temp?

 

[keri]

Originally Posted by candycane
http:///forum/post/2646376
Dinoflagellates and symbiotic zooxanthellae are pretty closely related.
Also the Derasa has a number of issues and I would have a couple of ??? (if you don't mind).
It doesn't look like there is anything picking at it, but if it is attached and it has a rock smashed up against it's shell (or is that something else on it's right?) it probably can't open all the way.
I put the rock up against it because it started leaning over while still being attatched. Should i take it out?
I would say a protozoan like WhiteSpot Disease, but it doesn't appear to be attacking the flesh of the clam or eating away at it. Usually WhiteSpot Disease is also much smaller.
I would look at Centralized Bleaching as an underline cause right now. if the clam was in to much illumination, and moved to another tank with too much illumination - it would caused Centralized Bleaching. So would tank temps that are to high though.
Is it up higher on the rocks and are you using a lot of t-5 lighting and is it just T-5 lighting? When you purchased the clam, was it mainly in the center of the mantle where the siphons are and then started to develope the spots later on? Or have you not owned the clam that long? What do you keep your tank at for specific gravity and how did you treat the dino? Also water temp?

It is about 1/3 of the way up (65g that is 24" tall) with 8 T5HO and was in a tank with MH when I bought it. This is a pic of the clam when I first put it in. The spots were less numerous then i think tho it's not the greatest picture. I *think* they were worse on the outside edges. I have had it since May 4th. My specific gravity is 1025 with a refractometer. Temp is 78. I treated the dinos with 4 days of darkness and several 10% waterchanges. Gradually brought the tank back to a regular photoperiod over a couple of days.
the fish i have are 2 false percs, a LMB (who eats pellets, not algae, doesn't bother the clam) a yellow wrasse and a scooter blennie/dragonet. I have looked for parasitic snails but the shell is clear.
I appreciate your help.
Old picture:

 

[candycane]

Yeah, you should probably move the rock.
When did you do the 4 days of darkness? Was the clam in the tank?
It looks most likely as if the centralized bleaching is beginning to become generalized. This to a clam is usually not good at all. However, most Derasas are not as light intensive as other clams such as Croceas.
If you can somehow seperate the clam from the rock or just move the rock, you might want to try lowering it away from any other creatures (corals, etc.) into the substrate and see if that begins to help. Seperating the clam from the rock would involve trying to see if you can spot the byssal threads and then slowly cutting them. If you rip out the byssal organ, the clam would 99% surely go. But I can see that there are bunch of Zoos behind the clam. It may be inhaling some sort of toxins from them.
All in all it's really hard to tell. There are just way too many variables.

 

[nycbob]

i agree with candy. move the derasa to the sandbed. they dont really need that much light. i hv my 2 on the sandbed, 20 inches aways from 6 t5 bulbs.

 

[keri]

the clam was in the tank during the blackout, it was a little over a week ago.
I'm scared to move it!! and unfortunately I think the rock it's on is in the middle of the rock wall... I was never good at jenga! I will try though, and I will move the zoos around it. I didn't know they would affect it, I've seen many pictures of clams with corals right next to them, even GSP growing ON them, is it ok only sometimes then?
I hope he makes it!
Originally Posted by candycane
http:///forum/post/2646419
Yeah, you should probably move the rock.
When did you do the 4 days of darkness? Was the clam in the tank?
It looks most likely as if the centralized bleaching is beginning to become generalized. This to a clam is usually not good at all. However, most Derasas are not as light intensive as other clams such as Croceas.
If you can somehow seperate the clam from the rock or just move the rock, you might want to try lowering it away from any other creatures (corals, etc.) into the substrate and see if that begins to help. Seperating the clam from the rock would involve trying to see if you can spot the byssal threads and then slowly cutting them. If you rip out the byssal organ, the clam would 99% surely go. But I can see that there are bunch of Zoos behind the clam. It may be inhaling some sort of toxins from them.
All in all it's really hard to tell. There are just way too many variables.

 

[candycane]

Well NO Tridacna Clam would be ok with going through 4 days of no light. The thing that I notice most if the Generalized Bleaching. It's just all over the mantle. Thing is, that the cause happened rather sudden. So it MIGHT be ok.

 

[keri]

Oh...I thought that because the corals would be ok then the clam would too...I didn't want to stress him out by putting him in another tank. So... I'm crossing my fingers that he gets better!

 

[mie]

My derasa is on the sand bed under a 400 watt halide. It is very healthy, good luck.

 

[keri]

I moved all of the zoos that were near the clam away but am unable to move the rock the clam is on without destroying the whole setup. I did move the rock that was wedged up against the clam.... I don't think 8T5HO's would be too much light if it was under MH before, no?

 

[keri]

Well...as of yesterday the clam had tipped totally over on his side, almost upside down on the rock (still open and stuff) so tonight I went in there to right it and it came undone, I was being very gentle but it wasn't hardly attached anymore (maybe by one string a hair's thickness) which came undone so I've set it on the sand and I'm hoping for the best (but expecting the worst) The underside doesn't look rough or torn, the byssal gland looks about the same as when I got it and there is just a tiny amount of stuff left on the rock where it was (not like other pics I've looked up where the byssal has been torn)
On the plus side I just looked and it's only been 5 minutes and it's starting to open up again and siphon normally *shrug*

 

[keri]

Update: Still alive on the sandbed, still growing like crazy...maybe the paler spots are just part of the colour?

 

[keri]

Hi I'm bumping this
I still have the clam, it's grown quite a bit, still has the same pale spots but otherwise looks colourful and healthy. I found a pic of another derasa that illustrates them more clearly (this is NOT my derasa)

I still have it under 8x T5HO but will be moving it to a 120 with 2x250 MH shortly.
You would think if it was sick it wouldn't keep growing? Or it would bleach out?

could it just be part of the colour? I'd like to get another clam in the future but I won't if this one is sick.

 

[nycbob]

all of those spots u hv pointed at look like part of the pattern, and not bleaching.

 

[jwagne267]

Thats def part of the pattern, matches the color to the pale purple on the inside too.

 

[keri]

Ok, good. Thanks!

 

[candycane]

The first picture that you posted is centralized bleaching, or at least I am 99% sure it is centralized bleaching. The last picture that you posted, are the clams eyes. But the MIDDLE part of the clam in the first part of the picture is where I am looking.

 

[mscarpena]

I agree with candycane 100%. I have a book by a german scientist and it is deffinately centralized bleaching. Candycane knows more about clams than I do, butI would say at this point moving it would be the worst thing you can do. The arros are pointing to the color pattern, but the bleaching in the center is not a good thing. I think moving it to new lighting would be a bad more and will probably make the centralized bleaching wose and could kill them clam. If you do move it I would do it very carefully and try to replicate it's current conditions to the T. Good luck and yes if it's still growing thats a good sign. Bleaching is a loss of symbiotic algae and if the clam loses too much of it the clam will basically starve to death. Also the old picture of the clam does not show any centralized bleaching.

 

[keri]

I need to clarify that the last picture, the one with the red arrows is NOT my clam, just one exhibiting simmilar pale spotting. The centre of my clam is not so pale, has more colour.
Are the "eyes" actually functioning? (ie: light sensing)
Thanks for the advice

 

[candycane]

The actual eyes may or may not be; it's hard to tell without looking at it under a microscope. But the eye is an iridophore made of irides with iride plates stacked up to form that. Then the only thing that really tells them apart from the other iridophores around the mantle are the addition of a hyaline structure which is (worst explanation) similar to a glass bubble.
I wouldn't say that moving it is a bad thing unless it is firmly attached. Zooxanthellae reproduce at a very rapid rate. It is possible that if moved, the zooxanthellae would grow very quickly again in that area. Just from the picture, I can't really tell WHY it is doing it. It could be that it can't open all the way, something is bothering it from the underside, a rock is blocking it from the light - but I have NEVER seen moving a clam turn out to be a bad thing if it is a good thing. As in if the clam is already heading south, moving it will probably continue to carry it south but if it just an enviroment factor that is causing it to bleach, it may rapidly fix it. Really no way of telling.