Whisker Shrimp

[Klaus3]

Acquired some "whisker shrimp" (Macrobrachium sp.) recently. I am not sure, if they are the Indian species (M. lamarrei) or the Burmese (M. lanchesteri), as both are similar? Indian ones have supposedly longer rostrum, but hard to tell in photos.

 

[Legit Fish]

from what i know these guys are pretty predatory and may eat smaller slower fish

 

[Klaus3]

I have no small fish in the aquarium - smallest are some type of stone loaches and rosy barbs. The species, that I have (which ever it is?) seem not strong or aggressive enough to catch most fish - so confusion with other Macrobrachium species?

The shrimp eat almost anything, including young snails, but have not attacked my fish. Both shrimp and fish seem to avoid each other mostly, but will steal food from each other. Need to feed them crustacean food at night, because the barbs will eat it or harass them during the day, if they have a pellet. Nocturnal and spend most of day inactive under a log, except when I feed the fish.

 

[Fishfur]

Do they have blue claws on the first pair of legs ? If so, they're the Indian one. I've kept them, and never had problems with them. Not aggressive to anything else, including Snowball, Bamboo and Ghost shrimp and numerous fishes, including kuhli loaches and a few nano species too.

Also never touched any of the larger snails.. but I could not say if they preyed on the small bladder or ramshorns, but not that I saw. The only critters I ever saw them prey on were newborn Snowballs and only if they found one. The population of Snowballs grew steadily with twelve Blue claws in their tank.

I also got a couple of other machro' shrimp that came with Blue claws. They were by catch I'm sure and while almost indistinguishable when young, once grown, they were very different. They were larger, had a dark red brown shade over their backs, had noticeably larger front claws that were quite dark red/brown. Actually fairly nice looking, but not nice shrimp to have in a mixed tank.

They were much more aggressive, much more predatory, and did in a number of Snowball shrimp and possibly a Ghost or two. Very secretive, they hid almost all the time, and were unbelievably hard to catch. The Blue claws were quite outgoing and spent a lot of time out and about, and never hid like this other species did. I never did figure out precisely what they were. The stress of catching them I think killed them, of two I had, neither lived long after I managed to catch them and put them in a smaller tank by themselves.

The blue claw colour is pale, and is easiest to see if they are on a light background.. white preferably.

Edit.. from the pic, the front claws are not dark nor large.. my guess is they are the Indian species

 

[Klaus3]

I have not noticed, that the claws are a blue tint. I thought, that the main difference was longer rostrum length on Indian species (as German name for this species "Langnasengarnele" mean "longnose shrimp"), but hard to see on photos.

They have done well - feed them Hikari crustacean pellets every night and they eat uneaten fish food during feeding times. Otherwise, hide during daytime. In last week, one shrimp moulted and is now rather larger and one of the females is now "berried". The eggs are light green.

I would guess, that the reports of predatory whisker shrimps are from misidentified juveniles of other larger more aggressive Macrobrachium sp. like M. assamense and M. rosenbergii. I have seen mine eat the young bladder snails and from larger population, now have only a couple large adults left. Interestingly, they not eat Malaysian Trumpet Snails, as they now slowly increase in numbers.

 

[Fishfur]

MTS have very hard shells, which make them a much more difficult target than bladder snails which have a surprisingly soft shell.

I am sure there are several species of smaller Machro shrimps, and the last time I looked online there still was not a great deal of information on them. The Blue Claw Whisker is one of these smaller species and such information as there is indicates they're from India, and an alternate name is Indian Whisker shrimp.

If I can ever scrape up the money, there's a super reference book, the title escapes me just now, but it's been translated from German, on just about all known shrimp species for fresh water. Friend of mine has it.. I'll have to see if I can find more about the small machro's in it.

When I first got the Blue Claws, the store warned me they could be aggressive, but they were entirely peaceful, didn't bother with any other tank mates.. they were like a slightly larger Ghost shrimp..[ palaemonetes sp.]... mainly arguing with each other over food tidbits. Females berried regularly, but I don't recall the egg colour now. They certainly ate baby Snowball shrimp when they found them, but not enough to noticeably slow down the growth of a population in a 29g tank with many fish species as well as other shrimps.

But the darker brown coloured ones that showed up as bycatch were so very different. Very shy, hiding most of the time, quite aggressive toward other shrimps, preyed on grown Snowballs and possibly juvie Ghosts. I never saw one eat a snail but they would have been able to manage small ones I am sure. Claw size was at least double that of the Blue Claws.