"Blue Prawn"

[Veneer]

What Macrobrachium species is this? (Blue tinge notwithstanding, it is, in all certainty, not rosenbergii).



I have seen it referenced only under the heading of "Macrobrachium sp. Mexiko" on German websites (accompanied by the identification serial of "P10"
on http://www.wirbellose.de/arten.cgi?acti ... &artNo=040). From the denomination, it apparently hails from the Mexican Neotropics. Is this the "blue prawn" (approximately 10 cm/4 inches in length [though I have personally observed a six-inch/15 cm individual] and aggressive to both conspecifics [this trait does not, however, prevent store employees from stocking them six to a single tank] and piscine cohabitants) stocked by American Petco chain facilities or does that dubious honor simply fall to subadult rosenbergii? In retrospect, I regard the latter possibility as markedly more probable.

Some images of "blue prawns" are available at the following link:

http://www.myfishtank.net/forum/showthr ... t=godzilla

As an aside, it has been stated that distinctly blue bodily coloration (not limited to the chelae) in M. rosenbergii results from a dietary deficiency- is this a misconception?

Finally, I have read of many instances in which Macrobrachium have surreptitiously entered aquaria in shipments of feeder ghost shrimp (Palaemonetes or Natantia); what raising/grow-out/collection conditions would facilitate such inclusion (particularly with monocultured North American "ghost shrimp")? I myself am in possession of what is most likely a young M. rosenbergii sold as such (at the "feeder shrimp" rate of 30 U.S. cents - for a three-inch specimen - as opposed to 15 dollars for a "blue prawn" per se).

[Mustafa]

I have seen it referenced only under the heading of "Macrobrachium sp. Mexiko" on German websites (accompanied by the identification serial of "P10"
on http://www.wirbellose.de/arten.cgi?acti ... &artNo=040).

--That just means that the German collector has no idea what species it is. It might not even be scientifically described for all I know since most shrimp species aren't actually.

Is this the "blue prawn" (approximately 10 cm/4 inches in length [though I have personally observed a six-inch/15 cm individual] and aggressive to both conspecifics [this trait does not, however, prevent store employees from stocking them six to a single tank] and piscine cohabitants) stocked by American Petco chain facilities or does that dubious honor simply fall to subadult rosenbergii?

--That dubious honor falls to subadult M. rosenbergii. I've seen those shrimp sold as you described. Most of the get crippled and die over time until one is left. By the way, they can get a lot bigger than 15cm. They can get up to 25cm and sometimes larger without the "arms".

http://www.myfishtank.net/forum/showthr ... t=godzilla

--Those are all young M. rosenbergii.

As an aside, it has been stated that distinctly blue bodily coloration (not limited to the chelae) in M. rosenbergii results from a dietary deficiency- is this a misconception?

--It's a misconception. They are naturally blue (especially the arms of the males) no matter what they eat it seems.

Finally, I have read of many instances in which Macrobrachium have surreptitiously entered aquaria in shipments of feeder ghost shrimp (Palaemonetes or Natantia); what raising/grow-out/collection conditions would facilitate such inclusion (particularly with monocultured North American "ghost shrimp")

--First "Natantia" is not a species name but just describes the suborder of shrimp among the decapods. That website you got it from uses it like a species name, but that's wrong. Second, "ghost shrimp" in the US (Palaemonetes sp.) are not cultured but caught from the wild. Third, M. macrobrachium do occur as an introduced species in southern Florida where Palaemonetes sp. also live. So, once in a blue moon a young M. rosenbergii might get caught along with the ghost shrimp. Another possibility could be that some wholesalers can get very young M. rosenbergii very cheaply and sell them as feeder fish. After all M. rosenbergii is cultured en masse even in the US (and worldwide) and very young shrimp should not cost all that much.

I myself am in possession of what is most likely a young M. rosenbergii sold as such (at the "feeder shrimp" rate of 30 U.S. cents - for a three-inch specimen - as opposed to 15 dollars for a "blue prawn" per se).

--Where did you get this shrimp? Do you have a picture?

Mustafa

[Veneer]

As to the young Macrobrachium sp. I mentioned: I noticed it around a month ago in a “Petsmart” tank with African butterfly fish (Pantodon buchholzi), “needle-nose gars” Xenetodon cancila (brackish-water, though not kept as such), and a bichir (probably Polypterus senegalus); in any case, a bad selection of cohabitants (it was probably separated from the main tank of ghost shrimp for ‘unneighborly conduct’). An employee, upon inquiry, stated it had been brought in by an aquarist who had presumably obtained it from another source and proceeded to rear it from “ghost shrimp” size. Though I made measures to correct her misconception, she (as is typical within such establishments) continued to regard it as merely a “big ghost shrimp” and it was under this heading that I purchased it.

[As of now, I have no digital camera, but images will be forthcoming.]

[bullosa]

It looks similar to the 'udang galah' in Sarawak rivers. It may grow to 12 inches (pincers included) and loves river bank caves.

I need to check out the scientific name but this is not a shrimp we would keep in our tanks.

[Veneer]

Actually, it has been established that the shrimp depicted is what is probably, as of now, an undescribed Mexican Macrobrachium species (what you have mentioned is the Southeast Asian/Indo-Pacific M. rosenbergii, a highly interesting, if belligerent, creature in its own right).

While M. rosenbergii is currently experiencing a slight resurgence in the North American aquarium trade and has received steady interest elsewhere (both for aquaculture and private aquaria), importation of the "neon blue prawn" is sporadic at best (and probably then only through shipment to Europe).

http://www.shrimpcrabsandcrayfish.co.uk ... ~mainFrame depicts a pair of ‘udang galah’ (scroll down to the “pole shrimp”) – clearly M. rosenbergii, and distinct from the “neon blue prawn”.

[Veneer]

It looks similar to the 'udang galah' in Sarawak rivers. It may grow to 12 inches (pincers included) and loves river bank caves.

I need to check out the scientific name but this is not a shrimp we would keep in our tanks.

I have and currently do keep young 'udang galah' (M. rosenbergii) and have found them to be a personable, if aggressive, species (my previous one came to recognize me, swimming to the front glass of the aquarium in anticipation of feeding).

[Veneer]

As an aside, has anyone else witnessed such conditioned behavior in Macrobrachium sp.?