[satguy2]

I have 2 cleaner shrimp and i don't know if it molting or dead? Does anyone have a picture of a molting cleaner shrimp or know were to get one? I think he is dead but want to make sure. I heard it is hard to tell between the too?
THANK YOU!!

[Poseidon]

Hi Satguy2, I can't help you with pics, or the shrimp. I will however move this to a more relevant forum...

[leebca]

Sometimes shrimp do have difficulty during their molt.

A molting shrimp takes cover. It hides since it is very vulnerable during this time. So the newly molted shrimp may be hiding from view. The molt looks like a shrimp only it has no 'insides' to it. Like a ghost of the original shrimp.

Do you add any iodine/iodide to the water? It helps shrimp molt properly and as often as they need to.

Go ahead and remove it from your tank. If it's a live shrimp, it will scoot away. If it is a molt, it will collapse when you take it out of the water. If it is a dead shrimp, it should be removed before it begins to pollute the tank.

Let us know how it works out.

[Ninong]

Originally Posted by leebca

Do you add any iodine/iodide to the water? It helps shrimp molt properly and as often as they need to.

It seems to me that shrimp in the ocean have no problems molting without iodine additions. Therefore, if one's aquarium water has NSW iodine levels (0.06 ppm, iodate and iodide combined), why would it be necessary or even safe to add additional iodine?

Excessive iodine is toxic. Shrimp handle this toxic iodine by depositing it in their exoskeletons and then molting to rid themselves of this toxic substance. Excessive iodine causes premature molting in shrimp. This much has been proven in controlled studies. That doesn't mean that shrimp require iodine additions in order to molt unless you can show me a tank with no iodine at all. In fact, I know of no studies at all that demonstrate that shrimp need iodine from the water column for any purpose. There is one study that shows that a certain species of shrimp grows optimally when the diet contains 0.003% iodine but no studies that show that shrimp require iodine from the water column. Just because the exoskeleton contains a lot of iodine doesn't mean the shrimp requires iodine in the water column. Accumulation of iodine does not mean that supplemental inorganic iodine is beneficial.

In a study of tankwater samples from 23 different reef aquaria, Dr. Ron Shimek found that none had iodine levels less than double NSW concentration. Some tanks -- those that were regularly dosed with iodine -- had iodine levels many times NSW levels. Since iodine is present in virtually all of the food we feed our tanks, it is highly unlikely that it will be depleted under most circumstances.

Many experienced reef hobbyists have never added iodine to their tanks and yet they have never measured iodine levels below NSW concentration.

[Ninong]

Originally Posted by satguy2

I heard it is hard to tell between the too?

One is an empty shell and the other one moves around, assuming it's still alive.

BTW, you won't ever see a freshly molted shrimp because they hide out for the first few hours after shedding their exoskeleton. The exception would be if you happen to catch them mating. Mating takes place within hours after one of the two shrimp molts. They couple together at the abdomen and the hard-shelled shrimp deposits a sperm packet into the receptacle of the newly-molted shrimp. A week later they will reverse roles and do it again. They molt approximately every two weeks and they will synchronize their molting schedules to maximize reproductive opportunities.

They are synchronous simultaneous hermaphrodites. The one playing the daddy role will be carrying eggs at the time.

[leebca]

Ninong,

When visiting the Shedd Aquarium and speaking with the Director he related a story to the group of how they were having difficulty getting their crabs to molt. A particularly expensive crab looked like it was going to die since it could not successfully molt. He had heard that iodine would facilitate such a molt.

It worked. He said he couldn't totally explain why and it's one of 'those things' that hasn't been determined. The Shedd Aquarium gets its water from offshore. Like you indicate, it is NSW. Your logic is good, Ninong but NSW didn't do the job.

The findings about the iodine creating a molt are probably correct.

[Ninong]

Originally Posted by leebca

One speculative consideration is that in a closed aquarium environment, the iodine is either artificially altered or removed from availability too quickly below a 'threshold' limit needed for good molts. Although the Director could measure iodine and saw it was at or just below NSW levels, when adding iodine/iodide to the water, there would be a 'group' molt.

So, to answer you question. . .I don't know. I know it works. For me a week after an iodine/iodide addition, I have a 'group molt.' Still, I measure it with the Salifert test kit, which is marginally of value.

There is no question that adding iodine will induce premature molting, that much is known. When I was little, I remember midwives giving pregnant women caster oil to induce delivery. I don't believe that proved that caster oil was necessary for childbirth.

It is likely that the sudden addition of iodine causes the crustacean's ability to deal with it to be overwhelmed, resulting in a hasty molt to rid itself of this toxic substance. So yes, it will cause it to molt but that doesn't mean that iodine additions are a good idea, especially regular additions of iodine.

I take issue with the blanket advice that is proffered by certain "hobby authors" that regular additions of toxic substances like iodine and strontium are required as part of good husbandry. They don't even mention anything about testing for these elements first. And some of these same "hobby authors" also sell the additives they are recommending.

Dr. Randy Holmes-Farley has written articles on both iodine and strontium that are balanced and a good representation of the issues involved. As far as I know, Genzyme (Randy's employer) doesn't sell either.

I used Salifert's iodine test kit, too. As hobby test kits go, I think it's probably accurate enough for our purposes. My measurements were always either 0.06 or 0.20 ppm total (iodate/iodide). I never added supplemental iodine. Based on higher measurements reported by other hobbyists who were adding iodine, I concluded that the iodine test kits might be reasonably useful, unlike the phosphate test kits which do not measure organic phosphate.

I asked Wayne Shang in an email once if he ever added iodine to his reef tanks. He's been at this for more than 20 years now and both his previous 300-gal tank and his newer 718-gal tank have been pictured in various books and magazines. He told me that he has never added iodine because his iodine levels have never fallen below NSW levels.

[leebca]

What Dr. Shimek proved was that iodine was in the exoskeleton. He speculated as we all are, why it is so. As far as I'm concerned that is still speculation. No one has shown why iodine accumulates in the exoskeleton.

I think Shedd's point was that the role that iodine plays is uncertain. That is why 'no one knows.' These creatures have to molt to grow/expand. Iodine/iodide plays a role. We can measure where it is, but the why seems to allude us. As far as you and I (or the professionals) know, there could be other trace elements involved yet to be discovered.

We may never know or understand the role of iodine in this process, in our lifetime.

I've run about 451 seawater samples through analytical laboratories. The Salifert iodine test kit doesn't match hi-tech analytical procedure results. But considering there are no other alternatives to the home aquarist, I agree it suffices. I particularly think it has value in measuring a change in concentration.

I never added iodine to my aquariums since I began in 1968 until just two years ago. I see an increased rate of molting. On the other hand, the shrimp are growing with each molt, so is the 'extra molts' a negative or positive or a neutral? Are they 'extra' or normal? I agree it isn't a necessary addition (otherwise I'd have a hard time explaining why my first shrimp in 1969 molted without additions ). So I add it, and think of it as being there "if they need it."

I don't buy nor sell iodine shelf additives. I, as a microbiologist and chemist, have access to chemicals from which I make my own additives and 'adjusters.' I'm talking a cost of less than $1. a month for my 700 gallon system.

What I'm confident of, and as the studies and experiences have shown is what I originally posted. . .It helps shrimp molt properly and as often as they need to."

I appreciate your contributions here Ninong. Thanks. Keep 'em coming!

[Ninong]

Originally Posted by leebca

What Dr. Shimek proved was that iodine was in the exoskeleton. He speculated as we all are, why it is so.

Actually I don't believe Ron has ever measured the iodine content of shrimp exoskeletons. He simply referenced other studies that measured the iodine content. The speculation is based on studies that have shown the toxicity of iodine to aquatic biota. Most of those studies involved freshwater species. There is very little research into the effects of iodine on marine species.

In particular, I'm curious to know the mode of biological transport. Is it absorption or adsorption? If iodine is added to the water column and this causes an (almost) immediate reaction in the crustaceans, is the iodine absorbed into the tissues and then deposited in the carapace or is it directly adsorbed by the carapace? Obviously dietary iodine is not involved here if we're talking about the effects of adding inorganic iodine to the water column to stimulate molting.

[Steven Pro]

Shouldn't there be some pretty clear, convincing studies from the food fish people? Shrimp aquaculture is big business and one would think they would have experimented with this.

[leebca]

I wonder. I monitor the aquaculture news. None of the literature I'm familiar with brings the matter up. Maybe a search of periodicals?

I think the matter may be beyond their interests. I mean, if they know that some iodine/iodide is necessary, do they need to know the exact mechanism? Iodine/iodide additions are so cheap. If iodine was more valuable than gold then I think it would have drawn attention and in an effort to find a substitute, the mechanism would be further resolved.

On the other hand, the bulk aquaculture of food shrimp is done outside the USA in farms that are a part of the sea and not a 'captive' or inland farm using any kind of artificial seawater. Even if they know of iodine, do they need a 100% molt? Under those conditions, losing a small percentage of shrimp that don't molt properly wouldn't be a concern. I wonder even how they handle all the molts that routinely occur during their growth?

[Ninong]

Originally Posted by Steven Pro

Shouldn't there be some pretty clear, convincing studies from the food fish people? Shrimp aquaculture is big business and one would think they would have experimented with this.

I did a google scholar search on this topic several months ago and I did come up with several studies that examined the toxicity of various metals but only one or two that mentioned iodine. And, of course, all you can read (free) on most of these hits is the abstract. Virtually all of the scientific journals are subscription restricted and the subscriptions are several hundred dollars a year.

Most studies resulted from a need to monitor effluent from industrial plants to determine safe levels of discharge (or whatever). And most were conducted in rivers and estuarine environments, not the open ocean. There have been a certain number of laboratory studies but I didn't find those. One study was referenced by Shimek but I haven't found it through google. According to Shimek, that study showed that "iodine is deposited in the exoskeleton" to rid it from the shrimp's body and then the exoskeleton is molted. Adding excessive iodine resulted in premature molting. I have no idea how excessive the additions were. Are we talking about 10 times NSW levels or 100 times?

Randy Holmes-Farley researched the topic of the effects of iodine on marine biota for his article on that subject but he couldn't find much of anything other than the iodine content of xenia, various macroalgae, crustacean exoskeletons, etc.

[Ninong]

After reading the following post in Randy Holmes-Farley's forum by someone who seems to know what he's talking about, I don't feel all that bad about not being able to find anything on iodine and aquatic crustacean molting in the scientific literature:

"Excellent, clear article! Coincidentally, I hid in the MBL library in Woods Hole on Sunday, hunting for any connection between iodine and crustacean biology. It continues to bug me that there is no apparent data backing up the lore about iodine and molting. Nada, and I looked hard. Maybe someday I'll write an article about the molt cycle in crustaceans, which is cool in its own right. Thanks for the hard work." You can read the full thread here.

Incidentally, I couldn't find iodine as a recommended additive to aid in shrimp molting on any of the shrimp aquaculture sites. I did find a 46-page DIY manual published by a trade association in Thailand that mentioned that some farmers were using iodine as an antiseptic but nothing about using it in the water to assist molting.