New Crocea Clam- signs of lack of light

[Dive_Master]

I bought my first crocea and she looks like has signs of light deficiency as described by D Knop.

I placed her 5 inches below the surface of the water under 250 W MH 10000K
lights that are 9 inches above the surface of the water.

I also have 40w PC Actinic right above her 9 inches above the surface of the water.

I am not sure if I should gradually increase the intensity of light by placing a frosted glass top in between the lights and the water or should I let her get as much light as possible.

The photoperiod for the MH is 10 hours, 12 Hrs for PC and addtional 2-3 hours of moon light.

I am new to clams and do not understand their needs yet.

[Ninong]

I bought my first crocea and she looks like has signs of light deficiency as described by D Knop.

What do you mean by "signs of light deficiency?"

[Dive_Master]

What do you mean by "signs of light deficiency?"

She is showing foggy (not really bleaching) areas by the excurrent siphon and anterior mantle. It is very slight but it looks like thin layer of "white slime", not real slime just looks like it.

Daniel Knop has some pictures of it in his book, but my clam has much less of it.


I do not know if I should give her more light or introduce her to the bright light gradually.

I lost some LPS and SPS corals before due to high intensity light without slwley accimating them and just do not want to make the same mistake with the clam.

THese MH are pwerful things that I totally underestimate it.

[Ninong]

Sometimes it is difficult to distinguish between what appears to be "bleaching" caused by a sudden increase in intense UV radiation and "bleaching" caused by a sudden reduction in the overall intensity of the lighting. I think we can probably exclude too much UV radiation as the cause of your clam's apparent "less than ideal" appearance. It is much more likely that what you are seeing resulted from the lack of appropriate lighting during the period of time since the clam was collected (if wild collected) or removed from the hatchery (if aquacultured) and the time that you acquired it.

It is quite possible that the clam experienced prolonged periods of darkness at some point, followed by various periods under different light levels. All of which would contribute to changes in the zooxanthellae in its mantle. This is why it is probably a good idea to acclimate new clams gradually by starting out with less light intensity and then gradually ramping up over a period of two or three weeks.

It is virtually impossible to provide too much light for Tridacna crocea clams unless you are sticking them too close to 1000w metal halides. However, if they were stressed out at some time in the recent past because of fluctuations in light intensity during the distribution process, then they will probably benefit from a period of gradual increases in light intensity. You could accomplish that by starting them out on the sand bed and then gradually raising them higher up in the tank over a period of two or three weeks.

I have two T. crocea and three T. maxima clams in my tank. Both croceas were electric grade and two of the maximas were ultra grade (same thing, just a different name used for the top grade). I placed both croceas at the very top of the rock structure in my tank immediately upon arrival without any problems whatsoever. Overnight shipment means that my clams arrived less than 18 hours after they were removed from their holding tank. That's not all that stressful, just an extra-long night.

I'm running two 250w 10,000K HQI DE lamps positioned 11" above the water's surface. Both of the croceas are located about 10" below the surface. The three maximas are located a few inches lower down. All five clams are on the rock structure.

During the first few months, my halides were running 9 hrs/day and all five of the clams thrived. Because of problems with overheating (no chiller), I was forced to reduce my metal halide photoperiod down to only 6 hrs/day. Within about three months after that reduction in photoperiod, both of the croceas lost a lot of the intense turquoise coloration in their mantles -- more of the brownish background color came through compared to their original appearance. Looking down on them from the surface of the water, I can still see a lot of turquoise veining in their mantles but looking at them through the front glass of the tank is disappointing compared to their original appearance. Both clams appear healthy but obviously they require more total lighting than I am able to provide at the moment if they are to regain their original electric grade appearance.

All three of the maximas have shown virtually no change in the coloration of their mantles. One is a gold maxima, so I didn't expect any change in its mantle but I was surprised that the two ultra maximas haven't shown any visible loss of coloration with the reduced lighting period. Once my chiller is installed, I intend increasing my metal halide photoperiod by half an hour per week until I am up to 12 hrs/day. That will take 12 weeks.

Getting back to your crocea clam. Try placing it low in your tank for the first ten days and then moving it higher up. The problem here is that once you place it on a rocky substrate, it may decide to attach within a matter of two or three days. Then it will be very difficult to move it. If you have a flat piece of rock in mind that you would like to use as it's final resting spot and if it's possible, place it on that piece of rock now and then place the rock and all on the sand bed. Then raise the clam and rock together.

[Dive_Master]

Thanks for the feedback. It was very helpful

One more thing. She is sitting on a flat pievce of rock, but the foot is about 1/2 to 3/4" above the bottom. Is this ok, oir should it really be placed so it touches the bottom.

[Ninong]

Thanks for the feedback. It was very helpful

One more thing. She is sitting on a flat pievce of rock, but the foot is about 1/2 to 3/4" above the bottom. Is this ok, oir should it really be placed so it touches the bottom.

The orifice at the bottom of the clam's shell needs to be in contact with the rock.

[Dive_Master]

Thanks

[Dive_Master]

Ninong,

Thanks for all your feedback

She just started to get aatached. I moved her more onto level rock, but still it is about 1/4 inches above the bottom where the foot is.

She stuck her foot out and I think it is trying to get attached with some stuff coming out

thanks