Derasa uneven growth

[heitlagerm]

Any suggestion on what can cause one end of the clam to show less/no growth?

It is about 3 inches and has been in the tank since March. It has attached itself to a rock since august about.

 

[dansyr]

Is there some slight shading or less reflective light coming from the right (in the first and last photo)? That would be my guess, seems to be less mantle extension there.

Does it get more mantle extension / open wider than the middle and last photo? If not, that's a sign there's some issue. Maybe it's more open in the last photo but hard to tell. Also the rock is probably not ideal (derasa are from very bright sand critters). Ideal is high light + sand, high light + rock is better than low light + sand IMO, but should think of a long term plan to get this guy in sand eventually.

How much light is it in? I would expect a little bigger growth band but its a good sign that it's still present. I have my derasa in 200-350 PAR of white-heavy light for context, i know people that grow them a lot brighter.

 

[exnisstech]

Not quite as uneven as yours but the growth band on mine isn't perfectly uniform either.

 

[heitlagerm]

Thanks for the replies. I was wondering about the shading myself. It does open wider than in the pic, however. I disturbed it to expose th white band.

I know the rock isn't ideal. But I am not going to disconnect him. But if he let's go I will move him.

Lighting is a DIY led system. Par looked to be OK, but could be a bit higher.

Today I increased the white light intensity. I will keep doing that slowly to see what will happen. Also, there is a rock outcrop higher up near it's right side. In the pic it does look a bit more shaded there. So I will look at that as well.

BTW, at 150 to 200 par, what is your photoperiod?

Thanks!

Marcel

 

[minus9]

At that par level, 8hrs minimum. If it's not long enough, just extend the peak period by an hour or two. Turn the intensity up until you start to see even growth across the shell.

 

[heitlagerm]

Just wondering, if I were to add a small strip light to focus in on the clam area... I see the orphek 12 inch light bars are on sale.
Might it be better to get the blue plus, reef day plus, or blue sky?
Reef day seems to mimic more shallow water.

 

[minus9]

Just wondering, if I were to add a small strip light to focus in on the clam area... I see the orphek 12 inch light bars are on sale.
Might it be better to get the blue plus, reef day plus, or blue sky?
Reef day seems to mimic more shallow water.

That could help and I would choose the reef day. Clams come from very shallow, clear water, so full spectrum is preferred.

 

[fish_collector]

Your derasa looks normal to me. If it starts to get a section of the mantle that doesn’t extend then that’s a sign of Pinched Mantle Disease and is caused by a protozoan, but easy to cure with a 30 minute fresh water bath. Yours doesn’t look like it’s unhealthy though. More par may even out the shell growth, and it may not. I personally wouldn’t be too concerned with it, if you start to see no new shell growth then that is a concern. Make sure your alk and calcium are up there and stable. Clams are one of the biggest users of alk and calcium in the tank.

 

[heitlagerm]

I moved the question regarding the specific light to lighting. Hope that doesn't count as a crosspost

 

[reefernc02]

Mabye run a icp till I started dosing trace elements from captivate I wasn’t noticing uniform growth and color on my clam but it has colored up big time although mine is a tridacna chimera