Clam ID, sold as Derasa but I think maybe Crosea?

[1979fishgeek]

Hi,

I’m looking for a iD on this clam, I purchased it 2 weeks ago and it’s settled nicely. It was sold as a Derasa, but it’s shell is not as smooth as I’d expect?

I was wondering if it could be a chunky Crocea, it’s really rounded, softball sized. It’s byssal area is large and within seconds of touching substrate it started digging into the sand and attached to the glass and you could see the gravel being shoved away. My other Derasa have much smoother flatter shells, slimmer byssal opening and don’t dig!

It’s colour is subtle shades of brown, gold, tan and a little mauve, and it extends the mantle over the edge of the shell.

 

[roboshark]

That’s a beautiful tank. Pure art.

 

[1979fishgeek]

That’s a beautiful tank. Pure art.

Thank you, it’s my pride and joy! 6x2x2 and a 5x 2 x1.5 ft sump. About 1000l

 

[1979fishgeek]

Just one more question, the suppler had it in the far corner of a very dimly lit tank. I’m wondering if the brown mantle colour is a reaction to this?

My tanks got WAY more light, so I planned to start it off on the substrate and work it up to higher light, I did not want to shock it.

 

[minus9]

It’s hard to tell from the pics, need a better top down pick of the mantle. Either maxima or crocea. You’re going to need a lot of light in that spot if you want it to grow. I would move it up to the top of your rock and enjoy.

 

[MartinM]

It’s hard to tell from the pics, need a better top down pick of the mantle. Either maxima or crocea. You’re going to need a lot of light in that spot if you want it to grow. I would move it up to the top of your rock and enjoy.

Yep, 400+ PAR and clams don’t need light acclimation.

 

[vetteguy53081]

Hi,

I’m looking for a iD on this clam, I purchased it 2 weeks ago and it’s settled nicely. It was sold as a Derasa, but it’s shell is not as smooth as I’d expect?

I was wondering if it could be a chunky Crocea, it’s really rounded, softball sized. It’s byssal area is large and within seconds of touching substrate it started digging into the sand and attached to the glass and you could see the gravel being shoved away. My other Derasa have much smoother flatter shells, slimmer byssal opening and don’t dig!

It’s colour is subtle shades of brown, gold, tan and a little mauve, and it extends the mantle over the edge of the shell.

Not the best light and image but may well be crocea

 

[Propane]

I don’t know anything about clams but I gotta say nice tank!

 

[1979fishgeek]

Yep, 400+ PAR and clams don’t need light acclimation.

I’ve got two books about clams “Giant Clams in the Sea and Aquarium by James Fatherree” and “Giant Clams: A Comprehensive Guide to the Identification and Care of Tridacnid Clams by Daniel Knop” which both agree light shock from inappropriate acclimation will cause localised bleaching which is very difficult to reverse. Which is why I started mine on the bottom, can you point me to where you read they don’t need light acclimation? This is interesting.

 

[minus9]

I’ve got two books about clams “Giant Clams in the Sea and Aquarium by James Fatherree” and “Giant Clams: A Comprehensive Guide to the Identification and Care of Tridacnid Clams by Daniel Knop” which both agree light shock from inappropriate acclimation will cause localised bleaching which is very difficult to reverse. Which is why I started mine on the bottom, can you point me to where you read they don’t need light acclimation? This is interesting.

I agree, there should be some sort of acclimation, especially if there's a huge difference between systems (LFS to home, etc). The acclimation shouldn't go for weeks though, it should be over the course of a week or sometimes less, just depends on how long the clam has been in lower light and the overall health of the clam. If there's no new growth, then I wouldn't wait too long and get the clam to proper levels over a matter of days. Observation is your friend for each situation.

 

[1979fishgeek]

I agree, there should be some sort of acclimation, especially if there's a huge difference between systems (LFS to home, etc). The acclimation shouldn't go for weeks though, it should be over the course of a week or sometimes less, just depends on how long the clam has been in lower light and the overall health of the clam. If there's no new growth, then I wouldn't wait too long and get the clam to proper levels over a matter of days. Observation is your friend for each situation.

Thank you, I’ve moved into a brighter spot and will raise it again in a couple of days. It’s already getting slightly better colour after just a week, so I’ll monitor it closely and fingers crossed it’s acclimates. I feed live phyto every day and all my clams ‘pulse’ open and closed when the foods added which I hope is a good sign. My other clams have clear growth on the edges of the shells in the positions they are in. I’m using 150ml a day each of Part 1 and Part 2 (Reef Zlements PH Plus) and kalk in RO which is a good increase since adding clams few months ago.
Quick Parameter check tonight:
PH 8.3
Alk 9.0
Calcium 472
Magnesium 1389
NH3 0.0
NO2 0.0
NO3 12 (I dose Nyos Nitrate plus - 10ml daily)
Phos 0.06

Crocea I thought were a more difficult clam, so I’m very keen to get it in the right spot. I did notice when I moved it’s foot seems to have quite a deep hollow under the shell. It’s seems clean and reacts to being moved digging quickly into the substrate but it was not attached the glass bottom as I hoped. Certainly a much larger foot than my Derasa and Maxima. I’m wondering if the foot was torn off by the seller or if this typical of Crocea?

Sorry for the poor photo, I’ve got a old phone and the whites were ramping down.

Really appreciate all your help. Thanks

 

[minus9]

Feed phyto to the tank, which will help the food chain, but don’t consider this feeding the clams. Just remember, when clams are pumping, it doesn’t mean they’re actually eating the phyto, they could pass it right through without actually eating it. You’ll want to put the clam at the very top of your rocks with the most intense lighting. It’ll be much happier there. Crocea will want to attach asap, it probably won’t bore, but it will secure itself in place. Derasa will lose its foot eventually and close the byssal opening as it gets bigger, same for all of the “big” species.

 

[MartinM]

I’ve got two books about clams “Giant Clams in the Sea and Aquarium by James Fatherree” and “Giant Clams: A Comprehensive Guide to the Identification and Care of Tridacnid Clams by Daniel Knop” which both agree light shock from inappropriate acclimation will cause localised bleaching which is very difficult to reverse. Which is why I started mine on the bottom, can you point me to where you read they don’t need light acclimation? This is interesting.

Because they self acclimate, and because where they are cultured they receive far more light than any aquarist will be providing them because they are cultured and full sunlight at 1000 to 3000 PAR. I have 20 clams, and I’ve been keeping clams on and off for 30 years. I have never acclimated a single one nor needed to.

 

[OrionN]

That is a Crocea for sure. It needs a lot more light than a Derasa

 

[1979fishgeek]

That is a Crocea for sure. It needs a lot more light than a Derasa

I’ve been steadily moving the Crosera up over a period of weeks. It’s actually not extending the mantle as much as it was on the bottom but it’s under a lot more light now and probably just regulating the light itself. It’s firmly attached to the rockwork as well.

Lighting over this tank is:
Maxspect RSX300 (300 watts), 4 x Orphek OR3 (60 watts each) and I’ve added a additional full sprectrum LED Lominie Asta 120 (80watts). I’ve also got another 2 OrpheK ORS Reef Day to add once it’s ready.

It’s already showing new shell growth, colours changing to more purple/mauve and less muddy brown grey.

 

[1979fishgeek]

Better photo.

 

[OrionN]

This is a Crocea, No other Tridacna clam species with byssal opening this big. All the other also point to Crocea but this is the money shot right here.

 

[1979fishgeek]

This is a Crocea, No other Tridacna clam species with byssal opening this big. All the other also point to Crocea but this is the money shot right here.

Yeah totally agree, the byssal opening when I turned it over was my first indicator that it was no Deresa. Lol

Thank you

 

[1979fishgeek]

Just updating this thread to show you the speed the Crosera been growing since it was moved up in the tank.

This was taken on the 30th October so only about two weeks of growth under high PAR. Check out the new white shell growth! Normally the mantle covers the shell completely but I managed to get this shot while it was reopening after a shadow moved over the shell.

So thanks everyone who commented, your help was greatly appreciated.

 

[minus9]

Nice!