Iodide for shrimp - is this the right stuff?

[Blinky]

I recently purchased 3 shrimp (Atyopsis moluccensis). RTR keeps them successfully, and recommended using iodide in the tank to help them molt. I trust his advice and want to keep my shrimp healthy. No one at the two stores I visited yesterday and today had much advice or knew which product would be best so I thought I'd ask you guys for advice
I purchased Kent Marine Tech.I today and I want to make sure this is the right stuff before I use it. Here's what the label says:
'Tech.I Long acting iodine supplement for reef type marine aquariums. Tech.I Iodine supplement provides iodine in a unique triple release system for sustained availability to invertebrates. Provides free iodine, iodide and timed release iodide. Excellent for Xenia and all soft corals. Assists hard corals and helps prevent bleaching.
Directions: Add 10ml per 50 gallons tank capacity every week for three weeks. Reduce to half dosage in subsequent weeks..."
Since this is a marine supplement, should I be using it full strength (2ml/wk in a 10g tank)? I ask because I know many products designed for both marine and FW often recommend doubling the dosage for marine tanks.
Thanks for your help

 

[Kissofthegorami]

That is actually the kind most people use. I happen to have fond a freshwater iodine supplement that I use. No one really seems to know if iodine is good for fish, bad, or doesn't matter.. so if you have fish, only use a little bit. Following their directions would probably be fine or use a bit less.

 

[congealedmeat]

I've heard to use half the recommeded dose. I don't use it and my shrimp have molted ok so far...I've been thinking about buying some, is it expensive?

 

[Blinky]

Thanks
They're in a species tank, so there aren't any fish to worry about - I had intended to move them from quarantine into my display tank after a few weeks, but after doing some reading and hearing from others here on AC I've made the decision to keep them in this tank permanently so they won't have to compete for food or get pecked at by curious platys. I've planted the tank and bought some more decorations today to make them more at home.
[edit]congealedmeat, these little guys were expensive but it could be because they're relatively rare here and hard to get. I (happily) paid $12CDN each for my three little guys. The store where I bought them seems to have trouble keeping them in stock at that price, so it mustn't be too outrageous [/edit]

 

[congealedmeat]

heh, they're almost that expensive over here too, about 6-8 bucks...I bought one of those for about $3 one day and I think it's turned blue. That or my ghost shrimp did, because I've seen him both blue and red before, with the big white stripe.

I want to make a nano-tank with a few of these guys, some marimo balls and maybe some kind of plant that can grow out the top. I'm just not too sure about what sort of filter I should get.

 

[Veneer]

There is absolutely no empirical evidence that freshwater (and arguably, in the views of some, marine) shrimp can even take in aqueous iodine/iodide - or that, if so, such additions are positive; supplementation has even been implicated to cause toxicological reactions: anectodal accounts that shrimp slough immediately after the addition of marine iodine or otherwise experience an increased frequency of molting may reflect stress response spurred by deleterious internal or immediate external concentrations of iodine compounds.

At the risk of seizing upon a potentially extraneous point, I must note that freshwater shrimp [with the recognition that nutritional composition studies focused on freshwater shrimp, which are generally dietarily insignificant by virtue of small size (with such notable exceptions as some 26-inch colossi of the genus Macrobrachium) are few and far between] are noted for their markedly low internal iodine content (to the degree that individuals allergic to "seafood" rich in that element are able to consume them); the tissue of Macrobrachium rosenbergii, a widely aquacultured species, has only 18% of the iodine of comparable marine/estuarine penaeid prawns.

As I have stated before, molting complications (and lagging health in general) in freshwater crustacea is largely equatable to more broadly problematic water quality (i.e. excessive softness) and "pre-purchase" duress.

At the risk of stating the obvious, I must say that I do not add any supplements to my freshwater shrimp setups - I daresay their health has not been compromised as a result.

If you persist in wishing to ply your shrimp with iodine, I would suggest the provision of seaweed (dried or frozen, as for marine fish), certain blanched leafy vegetables, and high-grade (as opposed to largely nutritionally deficient fish/shrimp/squid meal) seafood-based flakes/pellets/frozen formulas.

 

[Veneer]

Blinky, what are your water parameters?

 

[Blinky]

I want to make a nano-tank with a few of these guys, some marimo balls and maybe some kind of plant that can grow out the top. I'm just not too sure about what sort of filter I should get.

Sounds like a fun tank
I wouldn't go too 'nano' with these guys, they can grow to 4" long. I'm hesitant about keeping three in a 10g on a long-term basis, but the tank will be heavily planted, well filtered, and there's always the possibility of another tank (yikes, MTS strikes again!) if they get really large *grin*
I'd get a fairly powerful filter for the size of the tank, they like to have some current in the tank.

Veneer, I'm open to all ideas - that's why I'm asking before supplying the shrimp with iodide. My tanks all have good conditions (NH3 & NO2 0, NO3 <10, PO4 </= 1 - everything is in my signature link if you want more detail) but what is considered 'excessive softness'? My KH is ~70ppm or 4* KH. In all three tanks the temperature is stable, the pH is stable, and 50% of the water is changed weekly.
The person who suggested using iodide with bamboo shrimp has been in this game a long time and has given me (and countless others) some very good advice and information in the past, and keeps these shrimp successfully using iodide to prevent molting problems (which tells me he has evidence to back up his claim). I really trust his advice - I'm not blindly throwing chemicals into my tank, I want to do what's best for these animals.
I'd like to learn more about this issue, if you have links to websites or articles that discuss the topic I'd be very interested in reading them.

 

[Veneer]

Sounds like a fun tank
I wouldn't go too 'nano' with these guys, they can grow to 4" long. I'm hesitant about keeping three in a 10g on a long-term basis, but the tank will be heavily planted, well filtered, and there's always the possibility of another tank (yikes, MTS strikes again!) if they get really large *grin*
I'd get a fairly powerful filter for the size of the tank, they like to have some current in the tank.

Veneer, I'm open to all ideas - that's why I'm asking before supplying the shrimp with iodide. My tanks all have good conditions (NH3 & NO2 0, NO3 <10, PO4 </= 1 - everything is in my signature link if you want more detail) but what is considered 'excessive softness'? My KH is ~70ppm or 4* KH. In all three tanks the temperature is stable, the pH is stable, and 50% of the water is changed weekly.
The person who suggested using iodide with bamboo shrimp has been in this game a long time and has given me (and countless others) some very good advice and information in the past, and keeps these shrimp successfully using iodide to prevent molting problems (which tells me he has evidence to back up his claim). I really trust his advice - I'm not blindly throwing chemicals into my tank, I want to do what's best for these animals.
I'd like to learn more about this issue, if you have links to websites or articles that discuss the topic I'd be very interested in reading them.

Some articles (general information on iodine supplements; their potential utilization by [marine] shrimp [I found effectively no websites that backed up speculation on freshwater iodine supplementation with quantifiable scientific support]; the biochemistry of molting in freshwater shrimp; trace element utilization by various crustacea; the endocrinology of molting in freshwater shrimp; etc.), divided among web pages, "white paper" abstacts, and aquaculture/mariculture reports:

Chemistry and the Aquarium (one section is specifically devoted to shrimp).

An Iodine Supplement FAQ from WetWebMedia (search within the page via "Ctrl+f" for specifically shrimp-related questions).

A discussion of iodine supplementations with some intriguing commentary concerning crustacean molting. [Moderators: I maintain qualms about posting to another forum but truly could not uncover any external source referencing all the points made on said board.]

Investigating the Composition of the Exoskeleton of Macrobrachium rosenbergii - an inquiry into the particulars of this freshwater prawn's molting cycle.

Stable Amorphous Calcium Carbonate Is the Main Component of the Calcium Storage Structures of the Crustacean Orchestia cavimana - though this study centered about a terrestrial organism, the points made about biominerals, ion reservoirs, and calcium storage strategies should remain in broader consideration.

SACCHARICTERPENIN FEED ADDITIVE - this study's conclusion that "results showed: Survival rate, weight gain rate and molting frequency were more higher in treatments than controls" should bring perspective to claims that iodine supplementation is the sole means of bringing about healthy growth and molting in freshwater shrimp, underscoring both the essential nature of proper dietary content (and, by extension, potential applications for aquaculture food additives in home aquaria) and the fact that shrimp may be maintained in exemplary condition without the specific addition of trace elements to the water column.

One of the carbohydrates that shrimp meet in natural environment might be chitin. And the question was raised [sic] is the chitin used by shrimp better than other CBH? Chitinase activity was measured in a 332 number of species and bacteria living in the gut showed chitinolytic activity for a number of species too. Gwinn and Stevenson (1973) have speculated that in Orconectes limosus, the major energy source is chitin, because chitin resorbed by the hypodermis before molting provides sufficient material for
both new chitin synthesis and energy for molting (1.4 kJ which represents around 25% of energy accumulated in intermolt period).

Chitin

Chitin digestion and assimilation occur and make a significant nutritional contribution to shrimp (Clark et al. 1993). Shrimps reared under experimental conditions tend to ingest exuvia of newly molted shrimp with a kind of avidity, which seems to be in relation to the fact that a diet is well-balanced or not. Some diets containing shrimp meal showed poor growth performance and glucosamine could have a beneficial action a new exoskeleton synthesis (Kitabayashi et al. 1971) even though the levels tested (0.5-0.8%) represent a small percentage. Dietary supplies of glucosamine could be insignificant
compared to the metabolic supply provided that a substantial amount of glucose be available ammonioemia in hemolymph is given to be high (1.6-1.9 mg/ 100 cc in the blood of lobster or crayfish; Florkin, 1966). However, Ross Stevenson (1983) mentioned a pathway for glucosamine involved G6-P
and F1-P. And this is contrast with the fact that glucose phosphorylation capacity of shrimp is low (probably less that in fish) and most likely, metabolism of glucose is poor in comparison to mammals.
In fishes, level of chitinase in blood and lymphomyeloid tissues is suppressor to the one in gastrointestinal tract [sic], indicating a diffusion role rather than a digestive capability for chitin. In shrimp such a statement do [sic] not apply.

Chitin synthesis in shrimp cannot be considered out of the molting cycle, which shows the evolution of organic reserves in the digestion gland. Renaud (1949) clearly demonstrated in crabs the variation in glycogen. Also Cuzon (1976) reported this in M. japonicus, and again glycogen in hypodermis, which
indicates an intense metabolic activity including important transport of nutrients from an organ to another, starting in stage C of the intermolt period and in preparation to the next molt. Such transfer [sic] imply hemolymph which dispatch nutrients to different tissues in which metabolism will be oriented according to a given period of the molt cycle.

(From http://www.uanl.mx/publicaciones/maricultura/acuiculturaV/gcuzon.pdf)

I do not deny that iodine is necessary, in trace quantities (as obtained via foodstuffs), for freshwater shrimp; the potential endocrinological effect of iodine metabolization is, to my knowledge, an uninvestigated branch of inquiry:

Artificial production techniques are based on the ability to induce reproduction and spawning in captivity, but knowledge concerning the basic mechanisms of these physiological processes is insufficient. In this research, the involvement of various endocrinological factors in the control of molting and reproduction were investigated in M. rosenbergii. Ecdysteroids which control molting, were additionally found to accumulate in maturing ovaries and to be present in newly-laid eggs, indicating a potential role in ovarian development and embryogenesis in this species. In addition, juvenile hormone (JH)-related substances were investigated, revealing the presence of the JH precursor, methyl farnesoate (MF) in the hemolymph. (MF) was seen to fluctuate during the molting cycle, suggesting that this hormone has a role in molting in addition to reproduction.

[From http://ss.jircas.affrc.go.jp/kanko/seika/seikah8/4-13.html]

Continuing along this track of thought, liquid iodine's alleged effects on shrimp molting (if, in fact, valid) may come through interference with "molting" and "molt-inhibiting" hormones:

In M. rosenbergii and most other species of decapod crustacea including crabs and lobsters, the physiological processes of molting and reproduction are inextricably linked and under the control of various hormones. Crustaceans, which are arthropods, bear much endocrinological similarity to insects, and differ greatly from vertebrate species. However, compared with insects, which have been studied more widely, little is known about endocrinological mechanisms in Crustacea.

It is well-established that ecdysteroids such as 20-hydroxyecdysone serve as “molting hormone* in Crustacea and are excreted from a tissue known as the Y-organ. On the other hand, peptides (molt-inhibiting hormone: MIH) originating in the sinus gland complex of the eyestalks exert negative influence on molting. In M. rosenbergii, molting occurs approximately once per month accompanied by growth of the animal. In females, reproduction occurs in synchronization with the molt cycle during which vitellogenin (yolk protein) is produced and ovaries develop and mature. This process is also under the inhibition of an eyestalk hormone: vitellogenesis-inhibiting hormone (VIH). In hatcheries and on prawn farms, the technique of eyestalk ablation has long been employed to induce female maturation; the basis of this is the removal of the eyestalks and thus the removal of the source of these inhibitory hormones.

While much progress has been made regarding negative control of molting and reproduction, it is unclear whether positive control mechanisms exist. Regarding molting, it is still not known what causes ecdysteroid titers in the hemolymph (crustacean blood) to surge just before a molt. It is also not known how the negative effects of VIH are lifted, enabling the animal to produce vitellogenin for uptake into the ovaries. In insects, juvenile hormone (JH), which is a larval developmental hormone, also appears in the adult female to stimulate yolk protein production and uptake. At JIRCAS, we are interested in the functioning of juvenoid substances in M. rosenbergii and are attepting to determine whether such hormones exert similar influences in crustacean species. At present, we have detected a JH-precursor molecule, methyl farnesoate (MF) (Figures 2a,b), in the hemolymph of M. rosenbergii. It was expected that MF would be present in only females undergoing ovarian maturation, but it was detectable in both females and males without connection to reproductive events. MF was also seen to fluctuate during the molting cycle, suggesting involvement together with ecdysteroids in regulating molting.

From Molting and reproduction in the giant freshwater prawn, Macrobrachium rosenbergii: Endocrinology and potential aquaculture applications.

 

[RTR]

I have zero external data on adding iodide to FW crustaceans, but I had chronic molt-death issues some years back trying to keep M. rosenbergii in tanks, and heard the suggestion on using iodide. No more molt issues, and a nice foot-long shrimp in my tank. The first batch of Wood shrimp I tried all died over a period of months, all in failed molt. This batch is doing fine with supplement, I use Seachem's, 1/2 suggested dosage after water change (40-50% weekly).

My water is harder than yours, GH9, KH7. My ammonia & nitrite is undetectable always, nitrate ~10ppm (I supplement), phosphate ~1ppm (also supplemented), potassium (supplemented but not tested for), Seachem Flourish added weekly (all of this for the plants). The Wood shrimp tanks is a 33XL, lightly planted, with a 15 veggie filter attached (obviously very heavily planted).

Frank Greco (commercial dealer and owner of the FW shrimp mailing list) iodide supplments his shrimp as well. and for the same reason - pragmatism based on reduced deaths during molt. If I have deaths frequently when I don't use it, and few to none when I do, it works for me and I will continue using it. Others may make their own choices.