Pinched Mantle

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Lazys Coral House

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Hi Dr. Mac, hoping you can share some of your expertise regarding clams and what is commonly called Pinched Mantle. Their is information going around that pinched mantle (the symptom) is caused by a protozan. I have suspected it is just a clam that is not healthy from either tank conditions or shipping stress or someother aliment like pyramid snails etc... With your experience do you have any insight into this? Do you think it is a protozan/bacteria or general health/tank conidtions. If it is a protozan/bacteria and not a environment issue is it treatable?
 

PacificEastAquaculture

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Unfortunately I don't have a definite answer for you on so-called pinched mantle, but I can relate some experiences and observations from my past 16 years of dealing with many thousands of these animals.

I think so-called Pinched Mantle is likely just a symptom of other problems with the clam, just as RTN is often cited as a problem with SPS corals when mostly it is just a symptom of the coral dying and the tissue peeling off. A pinched appearance to the mantle is likely a symptom of other problems such as starvation, improper environment, predators and pests, or possibly true disease. Not enough is definitely known unfortunately, but many anecdotal observations are available. Clams can look great one day and be dead the next or start with a pinching to the mantle and slowly recede over days or weeks. Generally once the pinching begins it is too late to do much to salvage the animal. Freshwater dipping has been tried with limited success, again once the problem is observed it may be too far gone and the problem of pinching could originate from a parasite where dipping might help or may be from many other things that dipping will only put an already stressed animal further down hill.

I have traveled to French Polynesia and observed clams in the wild and set up a clam farm there with a local fisherman experienced in the pearl culture trade, and met with the President and legislature there about starting the farm and changing some regulations.

Clams there are an important and strategic food source and within the region, so clams are handled as a commodity not as a pet and this leads to problems with wild collected animals. They are shipped dry from remote islands where they are plentiful to Tahiti where the holding and shipping facilities are located. There are hundreds of millions of Maxima clams naturally occurring in French Polynesia, to the point that some small remote islands are made from clam shells so collection for the hobby has zero impact on wild population. Some local research has been done related to parasites, but again not much is known about treatment. In Tahiti 7 or so years ago we came up with a protocol for preventative freshwater dipping, but had limited success with actually affecting the parasite and not the clams.

Some other observations: In the wild in French Polynesia the reefs where clams are abundant are occasional rock outcroppings rather than large expansive reefs. Clams are found mostly embedded in rock giving them a firm and safe home and preventing predators or pests access, in your tank they need a firm rock base to attach. In the wild they are never found more that 5-6 feet below the surface in crystal clear waters under unrelenting tropical sunlight. They need very intense lighting. Few fish are found in the areas where clams are plentiful, where we culture them, in a different region, they must be covered to prevent nipping. I hesitate to say this, but it is true in that region, the temp where clams are most abundant is cool to cold, yes even in tropical French Polynesia. The most diverse population of clams I found there were in an area where the water temp was in the 60s and currents were so strong it was nearly impossible to dive in the region! Granted, this was on one particular trip , of many, and within one region but did have the best population. I spent several days on that remote reef observing. I'm not suggesting we run our tanks like that, just an observation from the wild. I think the only way to go is to keep cultured clams since at least in my experience wild clams are adapted to a completely different environment than we keep our tanks, in general. Cultured clams are much more use to varied conditions and warmer Temps, less flow, etc. We grow cultured clams on screens so when shipped the foot is never damaged, wild collected clams are chiseled or torn from the rock. Unfortunately often where the culture work is done there may not be fish such as wrasses present that can naturally control pests so careful observation and a strong brushing of the shell for new acquisitions is always a good idea. Aiptasia are often found on the shells but easily removed with brushing. During transit clams need to be kept cool, overheating stresses them. In an aquarium they need intense light with a good fish population of friendly neighbors because they do best in tanks well fed so that there are some dissolved organics, they may starve if not enough light and too pristine of a tank. Obviously, try to buy a clam with good mantle extension although this is not an ironclad assurance of a healthy or unhealthy clam. I know trying to take photos for my site often the clam closes slightly due to a shadow and I get too impatient and post a photo of a clam not as open as it really is, or you may walk past some clams in a store and they reflexively close slightly, a good sign, but not advantageous for selection. Bottom line, I would recommed to buy only from a reputable dealer such as myself. However, that is a meaningless and totally self serving statement, although still a good idea :)
 
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Lazys Coral House

Lazys Coral House

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Thank you so much for sharing your years of experience. I really appreciate you taking the time to write this post. It is very helpful to me and I hope others. I am defintley going to get a couple of your clams. Thanks again!
 

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