Derasa not growing

[jrp1588]

I've had a small derasa about 2.5-3" since January. He has always had great mantle extension and is always very reactive to light and motion. I have him in an SPS tank with plenty of light, calcium, and alk (I don't test, bad me. I'm growing acros like gang busters though, so it should be good.)

I've never once seen any new looking shell on him. Is he just doomed to die a very very slow death, or is there something I can do?

 

[j_mazzy]

selenium maybe?

 

[jrp1588]

selenium maybe?

I have no idea what that is.

 

[j_mazzy]

a mineral for bone growth

 

[MondoBongo]

no growth edge on the shell at all?

how are his reactions to stimuli like being shaded or picked up?

any chance he can in with snails? what else (moving critters) are in the tank with him, perhaps harassment?

pictures would be quite helpful.

 

[jrp1588]

no growth edge on the shell at all?

how are his reactions to stimuli like being shaded or picked up?

any chance he can in with snails? what else (moving critters) are in the tank with him, perhaps harassment?

pictures would be quite helpful.

No growth that I can see. It's purple coraline from top to bottom. He reacts strongly to stimuli of all sorts. He's always very full and open. All the fish pretty much ignore him entirely. My kole tang will very occasionally peck at his shell as he's passing by, but that's really not often at all. I'll try to get some pics tonight.

 

[MondoBongo]

it could be that he is still settling in perhaps. you've only had him about 4 months now, correct?

if you're growing SPS with no issues, then water quality shouldn't be a huge concern. most of the issues i've had with Tridacna not growing shell are related to either them not being in good health in general, or elevated no3 levels. typically if they're not in good health generally, they die faster than 4 months, and usually they are far more tolerant of unstable/less than ideal parameters than most SPS would be.

any possibility he's not getting enough light?

mantle extension and coloration sound like they're as expected? no gaping on the inlet siphon?

 

[jrp1588]

He's gaped maybe a couple of times since I've had him, and never for more than a few hours. I got him back in January, so he should have died by now if he was just a weak specimen. He's in a standard 125gal at the bottom under a Reefbreeders Photon 16 at a peak of 60 blue 30 white ramping up and down through the day. It's my understanding that derasas aren't very demanding of light, so he should be fine. I've got SPS only a couple inches above his level that are growing fine.

 

[jrp1588]

I made him mad so I could get a good shot of his shell edges.

 

[MondoBongo]

So I guess the best I can say is just keep him happy, and see if he grows. You're right, there's nothing there as far as growth edge.

But as long as he has adequate light, which it sounds like he does, and the water chemistry is correct, which if you're growing sps it should be, maybe he'll start to grow?

 

[jrp1588]

So I guess the best I can say is just keep him happy, and see if he grows. You're right, there's nothing there as far as growth edge.

But as long as he has adequate light, which it sounds like he does, and the water chemistry is correct, which if you're growing sps it should be, maybe he'll start to grow?

Haha, alright, well I'll continue to do nothing.

 

[MondoBongo]

Yeah unfortunately it's not a great answer, or even a good one, but aside from providing the conditions for them, there's not much proactive action that you can really take.

 

[jrp1588]

No problem. I'm kind of a hands off reefer anyway.

 

[Gig 'em]

If your water parameters are all solid with plenty of minerals available for the clam then you shouldn't have a problem. Have you checked for pyramidal snails? Any parasites would stunt the growth of the clam. Also some clams are just not fast growers and some are. It just depends on the individual, tests have been done on the same aged clams in the same tanks and documented that some clams just grew faster than others.

 

[jrp1588]

I haven't seen any signs of pests.

 

[jrp1588]

Good news, I was taking a really close look at my derasa yesterday and noticed a thin white edge to his shell. It's probably no more than .5mm, but it definitely wasn't there before. Hopefully he's finally settled in and is about to have a growth spurt.

 

[jrp1588]

Growth edges are becoming much more pronounced now. I'm still not sure what's changed, but I'm glad.

 

[MondoBongo]

Maybe just a late bloomer. Glad to hear he's starting to grow.