No Growth From Gigas.

[Troy V]

So its been a year since I've upgraded the Gigas home, and I haven't seen any new shell growth in that time. The mantle color is back to its former glory, and system CA and Alk consumption are back up to pre move levels. I even added a 250 watt MH between the Hydra 52's for added light. Any ideas? Please brain storm this with me. I am at a loss. How long does it take for a clam to grow after a stressful move?

 

[dragon99]

That's a beautiful monster! Are you sure you want him growing?

 

[Yuki Rihwa]

WoW it's a beast! At its current size its quite already too big for your tank hehehe I would wish him to slow down rather then keep growing

 

[DSC reef]

I wouldn't worry about new shell growth. The mantle is extended nicely and the clam overall looks to be in great health.

 

[Troy V]

Thank you for your kind responses!

I agree it does seem to look healthy. But I have read so many times when a Gigas or any mature Tridacna gets this large they will just perish without showing any signs of stress. Just here one day, gone the next. I recently read an article from the Waikiki Aquarium where they lost 2 of their long time Gigas clams for no apparent reason. In retrospect they said they could see some subtle signs, but didn't react until it was too late. I am a little concerned that the lack of new shell growth could be that subtle sign.

 

[Troy V]

WoW it's a beast! At its current size its quite already too big for your tank hehehe I would wish him to slow down rather then keep growing

Upgrade time!! Let the planning begin!

The tank dimensions are 60"x30"x31" and right now the clam is 30"x 20"x18" when the mantle is fully extended. I would like to see another 10" linear growth before I would need to upgrade. The System is over 550 gallons, and I've plumbed the outer SPS and softie/LPS tank to supply the clam tank with a decent amount of nutrients and water volume to HOPEFULLY sustain it for a number of years.

This is still much better than where I had it before the upgrade. The tank was so shallow that the clam would blow water out all the time. I stopped using MH because the bulbs would crack when the water hit them.
240 (8'x2'x2')

 

[DSC reef]

Thank you for your kind responses!

I agree it does seem to look healthy. But I have read so many times when a Gigas or any mature Tridacna gets this large they will just perish without showing any signs of stress. Just here one day, gone the next. I recently read an article from the Waikiki Aquarium where they lost 2 of their long time Gigas clams for no apparent reason. In retrospect they said they could see some subtle signs, but didn't react until it was too late. I am a little concerned that the lack of new shell growth could be that subtle sign.

One of the toughest parts to keeping a clam is the fact they can decline rapidly without signs of illness. IME I've learned to enjoy the animal while it's alive because I've lost clams that seemed to grow every week with beautiful pearl white shell growth out of the blue and also experienced a squamosa we had for many years perish within weeks and nothing I could to do to stop it. That one hurt. I hate loosing any animal but that guy was with me from a 3" juvi to a 12"+ beautiful adult. Most friends and family new of the reef tank as the one with the big clam. Anyway, rant over. There one of our favorite reef animals by far.

 

[Dsnakes]

That clam is incredible!! I'm afraid I can't be of help on the topic, but I'm glad I got to see that monster

 

[Troy V]

Update:
After 4 months it looks like the new growth line has changed/reset. It is now about an inch or two lower than original growth line. At night when the clam does its normal retraction, it retracts to the new growth line not the old. Also this clam is literally sucking the life out of everything in the system. This wasn't as much of an issue with the old system because it was so established and had tons of nutrients from continuous feedings. Now my ATO is adding 2 gallons of KNO3 at a concentration of 50ppm NO3 for the last 6 days, and I have barley detectable nitrates.
You might not need to feed clams, but that will not stop them from consuming.

 

[DSC reef]

One of natures best filters

 

[Shigshwa]

That is mad! No chaeto, no ULNS, just the clam consuming that much NO3??

 

[Troy V]

That is mad! No chaeto, no ULNS, just the clam consuming that much NO3??

That is correct! It is remarkable.

 

[Skynyrd Fish]

Awesome!!

 

[Nart]

@Troy V Wow... that is a beast. So let me get the numbers straight, you are dosing KNO3 at a concentration of 50PPM NO3 per day... for the last 6 days, for a total of 300PPM NO3 within 6 days, and now your NO3 is nearly undetectable? Holy smokes...

I'm glad to hear your clam is doing well.
I am a new Derasa clam owner, it's about 3" right now... and I feed the tank phyto feast daily. Would you also recommend to keep Nitrates up around 5PPM?

 

[Nart]

Also, where are you looking exactly to see the 'new growth'?

 

[Troy V]

@Troy V Wow... that is a beast. So let me get the numbers straight, you are dosing KNO3 at a concentration of 50PPM NO3 per day... for the last 6 days, for a total of 300PPM NO3 within 6 days, and now your NO3 is nearly undetectable? Holy smokes...

I'm glad to hear your clam is doing well.
I am a new Derasa clam owner, it's about 3" right now... and I feed the tank phyto feast daily. Would you also recommend to keep Nitrates up around 5PPM?

Thank you!
It really depends on the system, and how your coral looks. For me my SPS started to turn pale and lacked any color contrast. But if you have color and everything else is doing well I really wouldn't worry about it. Especially since it is difficult to predict the correct amount of NO3 for your system. Too much can have a very negative effect. I would say that the phyto feast you are dosing would supply an ample amount of nitrogen to feed the system.

Yes you are correct I am dosing 2 gallons of RODI water that has a 50ppm of NO3 each day. Yesterday I dosed an additional 2 gallons of water on top of the ATO 2 gallons and still no noticeable change. Frustrating!

 

[Troy V]

Also, where are you looking exactly to see the 'new growth'?

It is hard to see. Maybe these are better. The mantle has retracted to the new growth line.

 

[saltyfilmfolks]

@Troy V , is the par and spectrum close to the same as the last tank?

Just curious.

 

[Troy V]

@Troy V , is the par and spectrum close to the same as the last tank?

Just curious.

It is higher in this tank. Before I have a single photon 48, par was around 150 peak. Now with the 2 Hydra52 HDs and 250 MH par is around 350. Spectrum is different though with the different lights.

 

[saltyfilmfolks]

It is higher in this tank. Before I have a single photon 48, par was around 150 peak. Now with the 2 Hydra52 HDs and 250 MH par is around 350. Spectrum is different though with the different lights.

My only outlandish thought would be a lack of a specific NM that effects growth(the MHs alone should cover that though) , or conversely too much of one or several that that’s causing photoinhibition. Stunting growth.
With clams I didn’t think that truly possible. Those par numbers and spectrum “should” be fine.
Odd. And interesting.

How long is the peak photoperiod?

Maybe we could ask @Dana Riddle what he knows about clams.