Macrobrachium- feeding, water changes, & behavior

[Veneer]

I currently possess, in a ten-gallon aquarium (to be upgraded as necessary to account for growth), a Macrobrachium sp. (rosenbergii is most likely, though, at this size, lanchesteri cannot be ruled out) around 8 centimeters in length. The tank has been cycled and established for over a year, is heated to around 76°-78° F, filtered with a Penguin bio-wheel, and is sparsely planted with an assortment of dried-bulb-grown Aponogeton, a tropical lily of similar background, and several “water ferns” (originally packed with gel in a plastic cylinder- the jury is still out on whether these are indeed true aquatics) in medium-grain gravel substrate. I regularly top off the tank with fresh water and conduct water changes every few weeks. The prawn appears to do well under these conditions, and has molted at least twice in the few months it has been in this setup.

My questions:

1. Should I be conducting water changes more frequently? Some shrimp-keeping aquarists apparently do not do so at all, but I feel doing so in my situation would be more precarious (e.g., greater bioload, in terms of both gross output and per-specimen proportion, and lower plant density).
2. I currently feed my shrimp a wide assortment of generic tropical flakes (Topfin & Aquarian), as well as shrimp pellets, Hikari “frog granules”, freeze-dried krill, and Tetrafauna Delica Bloodworms (suspended in a nutrient gel). Do you foresee any nutritional problems with this diet? Should I offer more vegetable or live food matter (I have observed it consuming dead plant fronds)? Is the risk of disease transmission low enough to be negligible if I were to provide feeder fish (~5 mm guppies)? I ask because my specimen inadvertently consumed a medaka-type "killifish".
3. What is one to make of anecdotal evidence suggesting that aqueous trace elements (namely iodine) benefit freshwater shrimp? While I know of studies suggesting that liquid iodine supplements are not bio-available to marine shrimp, does the same hold true for freshwater species?
4. Upon obtaining it (Petsmart employees felt it “just a big ghost shrimp”), I noticed an opaque/blackish blemish at the peak of its anterior ‘hump’ (I know images would better illustrate this, but I currently possess no digital camera). Through two moltings, this has neither improved in coloration nor expanded. As this is strongly reminiscent of the white-spot syndrome that claimed a previous prawn, what measures should I take against this, if any?
5. My prawn spends much of its time clinging to the interior silicone marking the intersection of two glass panes, venturing down only to forage or groom. Is this by any means unusual? Will it become more ‘benthic’ as it grows?

Any information would be appreciated.

[Mustafa]

1. Should I be conducting water changes more frequently? Some shrimp-keeping aquarists apparently do not do so at all, but I feel doing so in my situation would be more precarious (e.g., greater bioload, in terms of both gross output and per-specimen proportion, and lower plant density).

--Depends on how frequently you feed your shrimp. If you feed him/her heavily every day, then I'd recommend a 10-20 percent water change a week. Also, regular feeding combined with regular water changes stimulates growth (i.e. shrimp grows faster than without regular water changes).

2.

I currently feed my shrimp a wide assortment of generic tropical flakes (Topfin & Aquarian), as well as shrimp pellets, Hikari “frog granules”, freeze-dried krill, and Tetrafauna Delica Bloodworms (suspended in a nutrient gel). Do you foresee any nutritional problems with this diet?

--None whatsoever. Nothing additional is really needed.

Should I offer more vegetable or live food matter (I have observed it consuming dead plant fronds)?

--Macrobrachium shrimp are omnivores and will eat anything they can find, including plant material. If you can find some hair or string algae in another tank then you can feed it to the shrimp (My Macrobrachiums love that stuff). However, it is not necessary as the fish food you mentioned above is more than enough for them.

Is the risk of disease transmission low enough to be negligible if I were to provide feeder fish (~5 mm guppies)? I ask because my specimen inadvertently consumed a medaka-type "killifish".

--Since they are opportunistic omnivores they will consume whatever "runs" into their claws. However, once again, life food is not needed for their well-being. As to disease transmission....there is always a chance although I have not personally observed anything to that effect.

3. What is one to make of anecdotal evidence suggesting that aqueous trace elements (namely iodine) benefit freshwater shrimp? While I know of studies suggesting that liquid iodine supplements are not bio-available to marine shrimp, does the same hold true for freshwater species?

--Absolutely not needed. I have never used a single drop of Iodine in any of my shrimp tanks and my shrimp are healthy and reproduce like rabbits. And no...Iodine in the water does *not* help with molting as some people have suggested in the past. The shrimp will get more than enough Iodine from the food they eat. Both flake food/pellets and algae have more than enough *usable* Iodine content. Shrimp are not sponges that just suck up Iodine out of the water...

Also, a lot of shrimp species come from small rivers which are almost devoid of any trace elements. The shrimp seem to do just fine in their natural habitats without some well-meaning hobbyist going to the creek/river and pouring some Iodine in the water...
I think you get the idea...

4. Upon obtaining it (Petsmart employees felt it “just a big ghost shrimp”), I noticed an opaque/blackish blemish at the peak of its anterior ‘hump’ (I know images would better illustrate this, but I currently possess no digital camera). Through two moltings, this has neither improved in coloration nor expanded. As this is strongly reminiscent of the white-spot syndrome that claimed a previous prawn, what measures should I take against this, if any?

--Hmmm...good question. Is the shrimp behaving normally? Unfortunately, there is not much known about shrimp diseases so that we have to "experiment" to find out. I have used Metranidazole (Fish Zole Brand) and Kanamycin in shrimp tanks without adverse effects before. You can try that and see if it helps. First, make sure that the shrimp is really suffering from a disease.

5. My prawn spends much of its time clinging to the interior silicone marking the intersection of two glass panes, venturing down only to forage or groom. Is this by any means unusual? Will it become more ‘benthic’ as it grows?

--Although Macrobrachium shrimp do like climbing around, they usually do not constantly cling to the silicone area as you described above. Did you provide it with some hiding place in there? Many Macrobrachiums like some kind of cover under which they sit for extended periods of time.

Any information would be appreciated.

--I hope this helped somewhat.

Mustafa

[Veneer]

3. What is one to make of anecdotal evidence suggesting that aqueous trace elements (namely iodine) benefit freshwater shrimp? While I know of studies suggesting that liquid iodine supplements are not bio-available to marine shrimp, does the same hold true for freshwater species?

--Absolutely not needed. I have never used a single drop of Iodine in any of my shrimp tanks and my shrimp are healthy and reproduce like rabbits. And no...Iodine in the water does *not* help with molting as some people have suggested in the past. The shrimp will get more than enough Iodine from the food they eat. Both flake food/pellets and algae have more than enough *usable* Iodine content. Shrimp are not sponges that just suck up Iodine out of the water... :-D

Also, a lot of shrimp species come from small rivers which are almost devoid of any trace elements. The shrimp seem to do just fine in their natural habitats without some well-meaning hobbyist going to the creek/river and pouring some Iodine in the water... :lol:
I think you get the idea...

What is your opinion on the conclusions made in this thread - http://www.reefs.org/cgi-bin/ultimatebb ... 6&t=000014 - namely:

As has been pointed out already, iodine is not required by crustaceans to molt. This was the "idea" a few years ago. I suspect that it came from the fact crustaceans would molt shortly after additions of iodine begin, or more regularly when they do. The molts also have an elevate level of iodine in them. So if you put those two together without further information then it seems like they need it to molt. But this is not the case. You would also get exactly the same observed results if iodine was toxic to them, and they used the molting process as a way to remove excess from their body. If you read up on the biology of crustaceans you will also find no mention of iodine in any way that is important to their bodily functions. That is the current theory anyway, and makes sense with the current information available.

?

4. Upon obtaining it (Petsmart employees felt it “just a big ghost shrimp”), I noticed an opaque/blackish blemish at the peak of its anterior ‘hump’ (I know images would better illustrate this, but I currently possess no digital camera). Through two moltings, this has neither improved in coloration nor expanded. As this is strongly reminiscent of the white-spot syndrome that claimed a previous prawn, what measures should I take against this, if any?

--Hmmm...good question. Is the shrimp behaving normally? Unfortunately, there is not much known about shrimp diseases so that we have to "experiment" to find out. I have used Metranidazole (Fish Zole Brand) and Kanamycin in shrimp tanks without adverse effects before. You can try that and see if it helps. First, make sure that the shrimp is really suffering from a disease.

It is feeding and moving about actively. I'll try to get some images as soon as possible.

5. My prawn spends much of its time clinging to the interior silicone marking the intersection of two glass panes, venturing down only to forage or groom. Is this by any means unusual? Will it become more ‘benthic’ as it grows?

--Although Macrobrachium shrimp do like climbing around, they usually do not constantly cling to the silicone area as you described above. Did you provide it with some hiding place in there? Many Macrobrachiums like some kind of cover under which they sit for extended periods of time.

Closer observation revealed that the shrimp, in truth, does spend a large portion of its time clambering about the faux driftwood and filter intake, as well as lurking beneath the plants; it practically leaps out of the tank upon noticing aquarium flakes on the surface.

[Mustafa]

What is your opinion on the conclusions made in this thread - http://www.reefs.org/cgi-bin/ultimatebb ... 6&t=000014 - namely:

--It sounds to me as if this guys is more informed than most people out there. He's confirming my points. As far as I was able to research Iodine *is* required by all living organisms as a trace element. However, as I also said before, the tiny amounts needed are already taken in with food and free floating Iodine in the water would be useless anyway. I totally agree with the rest of this person's post.

It is feeding and moving about actively. I'll try to get some images as soon as possible.

--Yes, a photo would help immensely.

Closer observation revealed that the shrimp, in truth, does spend a large portion of its time clambering about the faux driftwood and filter intake, as well as lurking beneath the plants; it practically leaps out of the tank upon noticing aquarium flakes on the surface.

--Sounds like typical Palaemonid shrimp behavior to me!

Take care,
Mustafa

[Veneer]

A question:

While I know that M. rosenbergii and M. lanchesteri are outwardly disparate as adults, the distinctions are (to some degree) less marked amongst juveniles.

Are the following images, respectively depicting young M. rosenbergii and adult M. lanchesteri, accurate enough (in terms of general coloration) to credibly aid identification purposes?

http://www.itbiztonsag.hu/shrimps/speci ... gii_e.html

http://www.akwa.aip.pl/macrobrzdj.htm

M. rosenbergii exhibits broad outward variability across its range, and (at least within my experience) may sport bluish carapace striation not inconsistent with lanchesteri. Could said species be distinguished – purely on the basis of external observation (I would like to rule out dissection) – at a mutual length of three inches? What growth rate would one expect a juvenile rosenbergii to assume under ideal conditions?

[Mustafa]

A question:

While I know that M. rosenbergii and M. lanchesteri are outwardly disparate as adults, the distinctions are (to some degree) less marked amongst juveniles.

--Actually, juvenile M. rosenbergii are immediately recognizable as rosenbergii if they are larger than about 2 inches. What is offered as M. lanchesteri in the hobby in Europe may not be M. lanchesteri at all but a name that some exporter conveniently gave his shrimp. Lots of times exporters go pick the name of the most common shrimp from very old books or publications for their mystery shrimp.

Are the following images, respectively depicting young M. rosenbergii and adult M. lanchesteri, accurate enough (in terms of general coloration) to credibly aid identification purposes?

--No, they are not accurate and actually plain wrong. See below....

http://www.itbiztonsag.hu/shrimps/speci ... gii_e.html

--This is actually not a rosenbergii at all. It's a very peaceful type of Macrobrachium that tiny claws in both genders. I have three of them in my tank right now. They get to be about 3-3.5 inches max and are from India. They are even more peaceful than the domestic P. paludosus.

http://www.akwa.aip.pl/macrobrzdj.htm

--As I said, I am not convinced this shrimp is M. lanchesteri. Knowing how names are just given without proper identification by exporters chances are very good that this shrimp is some other species.

M. rosenbergii exhibits broad outward variability across its range, and (at least within my experience) may sport bluish carapace striation not inconsistent with lanchesteri.

--They are actually not that variable. All the M. rosenbergii I have seen are immediately recognizable as such. I've seen life M. rosenbergii (both juveniles and adults) and dead ones (which I see every couple of days when I go down to Chinatown here in NYC...they are sold as food shrimp...whole with their long blue claws still attached).

Could said species be distinguished – purely on the basis of external observation (I would like to rule out dissection) – at a mutual length of three inches?

--Most definitely. At three inches you should have a small version of an adult M. rosenbergii running around in your tank...plus...you should be able to tell by their behavior. If you have fish in the same tank some of them will try to "jump" at the fish in mid-water trying to grab them. I observed this at Petco where they were kept in a tank with fish.

What growth rate would one expect a juvenile rosenbergii to assume under ideal conditions?

--Under ideal conditions these M. rosenbergii grows almost exponentionally (hence its use as a food shrimp). I don't have the exact numbers but do a google search and you will get lots of info about the growth rate of farm raised M. rosenbergii.

Mustafa

[xerxeswasachump]

I'm trying to identify what i think is a Macrobrachium shrimp. It is a long armed shrimp about 2 inches long with reddish body and claws. The claws are very small but it is very aggressive toward my fish. Should i be worried? The fish don't seem to really be bothered by it. I wouldn't mind having something around to eat baby guppies. I also have a male betta in the tank. Is he in any real danger?

[badflash]

The shrimp will have the fish eventually. Bet on it.

This is not a Rosenbergii. They grow explosively and don't stay at 2" very long. Mine went from 3/8" at the end of November to 4.5"+ now.

Here is a pic of my shrimp in mid January when they were 2"+.

Most of mine also have orange noses.

They now have well developed claws that can do some real damage. Even at 3/8" they were able to fend off a 1" guppy.

[xerxeswasachump]

Yeah mine looks nothing like that. It has red markings all over it and small front claws.