Crocea Question

[peerboerner]

I have attached a picture of my T. Crocea. He is sitting in the rock work of my 120 AGA Reef tank about 1/2 down from the surface of the water. My lighting consists of a PFO dual 175watt MH setup along with 3 (soon to be 4) 46" blue actinic lights powered by an ice cap 660 ballast. My water parameters are:

Salinity: 1.025
Ph 8.4 (mid day)
temperature during photo: 82 degrees
Alk. 9.0
Calcium: 420
Nitrite: 0
Nitrate: < 10ppm (lowest color on scale)
Ammonia 0
Phosphate: 0ppm
Mg: 1320
Photo period:
Blue Actinics: On at 9:00am off at 9:00pm (12 hrs)
MH: On at 10:00am off at 8:00pm (10 hrs)

I know my lighting is a bit shy for a Crocea and that's the purpose of this post. His mantle never extends the way it did at the store where I purchased him. The rim of his mantle is always a little "curled in" towards the opening of the clam. I've recently moved him from sitting on his "hinge" with his mantle pointing directly at the light to more of an angle. When his mantle was pointing at the light, it would not expand as much as it does now.

A missing tid-bit: For the past two weeks or so my aquarium temperature peaked during the day to nearly 88 degrees and often would hover around 86. I've taken several steps to correct this problem and the temp now maxes out at 84 just as the MH lights go out at night. Anyway, he looks stressed.

I'm on the verge of upgrading my lights to dual 250watt MH from their current 175 watt configuration. I'm just nervous about the heat. Any ideas what might be going on here?

Thanks in advance!

 

[Potsy]

I can't really be too sure from the picture but perhaps the mantle is a bit pinched and I wouldn't be surprised if the temperature spikes are responsible? How are you cooling the aquarium? I mounted a 8" Honeywell fan on the wall to blow across the length of the aquarium and the heater has to work pretty hard to maintain 78 degrees; without the fan, my aquarium can reach temperatures of 88-90 degrees. I think almost all overheating problems can be cured by a powerful fan (not those little computer fans) - it's noisy but it works very well. Do you have pendant fixtures? It's much easier to ventilate air with pendants.

 

[K. Lee]

Temperature spikes are bad, but, I haven't attributed, or noticed any particular temperature changes to clams. They appear sluggish and non-reactive to cold water, ie. shipped clams act like they are dead if the water is cooled somewhat.

T. crocea in general, IMO really hate current.

Hyperextension of the mantle means the clam wants more light. A clam getting the right amount of light will not angle it's mantle to capture more light, but will lay it out flat. A clam in a lot of current will have problems in achieving this, however.

Other clams seem to tolerate water current better than T. crocea can IMO/IME.

 

[peerboerner]

Thanks for the prompt feedback.

Potsy: I have an enclosed canopy to make the tank look like a lovely piece of furniture , which it does, but there's no possibility to use a large fan across the top of the tank as would be with pendants. I have two 4" fans, one aligned with each MH blowing air OUT of the canopy. There are also two 4" holes letting air in. I have also placed a 6" fan in the sump (no room for a larger fan.

I'd like to get the temp further down to say 80 or 82 max. I have a plan to add two more small fans to blow air INTO the canopy in addition to the two blowing air out. I'm hoping that the new INWARD blowing fans will force cool air onto the water's surface. If that fails, I may cut some righteous holes in the top of the canopy right over the MH bulbs to let the hot air rise out on its own... we'll see. I cringe when I think about doing that.

K. Lee: The clam is not in much current, but there is some - can't tell what the flow rate is, but I can see particles move ever so slowly past the clam when the light is right. Perhaps with the addition of more powerful lights, my clam will perk up further. In actuality, it's not that he looks bad, it's just that he doesn't look great - like the day I bought him.

Thanks again for the prompt response and listening to my thoughts!

 

[Potsy]

K. Lee:

I believe croceas are found on the reef top's surge zones (that's why they're often exposed to the air at low tide and deeply embedded in sps coral heads and rubble) and so are more tolerant of water turbulence than other tridacnids. My crocea sits in one of my aquarium's higher current areas and expands fully.

If your experience is different, perhaps there is less tolerance for current among farm-raised croceas cultured in relatively calm waters?

Peerboerner:

Perhaps you can position another fan to blow across your sump to induce more evaporation?

 

[K. Lee]

Potsy, that is what you would think, being in SPS corals, however, in my experience, IMO, that is not the case. I have never seen it written that T. crocea were found in turbid waters, actually, if anything, the opposite. I think T. maxima withstand currents a little better than T. crocea, but neither prefer turbulence, or anything close IMO.

Aquarium situations are vastly different than the ocean, so perhaps under natural illumination T. crocea may close up completely on a exposed reef crest, IF, they are indeed ever found there, and still have enough exposure to light to flourish.

I imagine most of the corals any T. crocea bore into in nature are on non-turbulent, protected from rough water sections of the reef.

Even in the low flow areas of my aquariums, T. maxima tend to move until they are getting reduced water movement over their gills or incurrent siphon. That is the T. maxima IMO/IME seem to prefer their excurrent siphon upstream in the water flow. I've noticed T. gigas seem to prefer slightly more water movement over their gills than T. maxima or T. crocea.

 

[Alex]

Well I would say that your lighting is ok for your clams. I have an electric green crocea that is about 20 inches from a 150MH and it is doing great. As for the picture it looks like the clam is a little pinched but nothing serious yet. I would check to make sure that there are no snails on the clam.

As for currents I have seen all kinds of clams take high and low flow. If it is pounding the clam directly it will not be happy but is all the water is moving and the clam is angled right there will be no problems and the clam will be happy.

I have seen a large maxima in a personal tank that was opened fully in water that was moving between 2.5-3 feet per second. I do not now how the clam did long term but it was opened all the way when I saw it.

Alex

 

[peerboerner]

Clam is enoying me, but at the same time, starting to look yummy

Clam is enoying me, but at the same time, starting to look yummy

Well,

Last night I decided that until my 250watt dual MH setup arrives to replace my equally expensive 175watt setup (thankfully I can reuse the sockets and reflecters ) I would place my clam on a rock directly beneath one of the MH bulbs. To do that, I had to move my favorite yellow sarcophyton and redirect my powerheads in order to provide flow for the leather... which caused me to move my otherwise thriving red montipora frag lest it topple over from the current... which lead me to move my clam a little more so as not to have it in the current deflected from the rock the sarcophyton was on... you get the idea. Anyway, I though't I'd "tack" the clam onto my rock work with some cya glue until I was sure it's placement was fine. Well, that stupid clam decided to cough causing the glue to give way and him to fall onto my sand bed. :mad2:

In Daniel Knop's book he show's native Indonesian fisherman eating giant clams raw during collection... I can see why.

Actually, once my 250's come, I'm sure the clam will thrive on the sandbed like all the others I've seen in this forum.

Thanks for all of your help and insight. I really appreciate it!