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Macrobrachium sp. choko

My neighbor and aquarium-friend Kees, who also happens to be a very good manager of his own edible-fresh-fish store, has one really huge tank and a smaller one but in his huge tank, the Macrobrachium is getting way too big. He has 5 of them and they eat his fish. When he got them, he had no idea how big they'd get and from their small size he couldn't find out what shrimp it actually was. Well, he eventually found out when they simply wouldn't stop growing and they also grew an appetite for costly tropical fish... :-)
Then one day he managed to catch one when it was getting ready to shed skin. His tank is so big, with many caves for hiding places that it's really hard to catch a shrimp that doesn't want to get caught. I temporarily adopted the animal until I find another hobbyist who can accommodate the beautiful beast. But maybe I'll keep it myself, or I'll take one of the next catches. He first checked the new tank for any exits, then he ate lots of live red mosquito larvae before going into hiding behind hardwood. During his exercise he uprooted the plants in the improvised tank that I'd made ready for him. I replanted them in front of the tank as he likes to have the back of the tank for his own hiding place, the part behind a big piece of hardwood. It's such a slender thing, awkwardly fragile and also so very big, compared to the Caridina serrata! I watched him eat and because of his enormous size it's possible to observe the mechanics of the limbs, especially the ones handling the food close to his snout. It's dark chestnut brown now, but Kees explained that after he sheds his skin he'll be a beautiful red. His tank is small but I'll get a somewhat bigger one for him and anyay I get the idea that he wouldn't be roaming about much in his natural habitat, keeping to himself in some dark spot and waiting patiently for the occasional tasty fish to come wandering his way, or catching some smaller critters in the mud (I wanted to write "critters in the crud" but alas, the dictionary tells me that word won't fit).
later note: Mating
(July 1, 2002) Witnessed a fantastic spectacle tonight.
This afternoon I got a new 60x30x30 tank, started it up and decorated it with plants and hardwood to make a better place for the Macrobrachium sp choko to stay over. Then Kees caught and delivered a small female from his tank where they must leave.
The male had just finished a tour of reconnaissance over his new tank and was calm in hiding, when out of the blue we dropped this small (half his size if that) female in his habitat. They seemed not to see or know one another and we started wondering, in this new light, if they are actually the same kind, also because his chestnut darkness is so different from her blue hue with her marbled look. Apart from size and color, they are identical, though. Well, her big arms seem shorter.
It took about ten minutes before they "met" and their antennae touched.
A shudder went through their nerves, I suppose, because they froze for a second and then started moving. The female moved away and the male went in clumsy pursuit. His impressive mega-arms were in the way when he tried to pass between plants where she'd passed, or he had big trouble rounding a corner that she's scuttled around easily.
Still they kept at it while all the time he was allowed a little bit closer before she took off again. The fanaticism in her flight got less and less. She allowed his fantastic arms to envelope her every now and then, when in fact these arms could not really force her to stay, they are so slender and inflexible. He climbed her back a few times but he was unable to get a grip on her hard slippery bodice and she slipped away, and away again, but delaying her escape more and more.
If he was frustrated about the seeming impossibility of mating, he had no way of showing it. He paused for a moment, moved his huge useless arms out of the way and went back at their game of gallant pursuit. Between two plants, in the corner of the tank, against a piece of hardwood, she was always ultimately elusive.
Finally he got a grip, on a spot where she could have easily gone away, he let her flutter up for a very brief moment, only to be able to grab her again and land her on her side, then his left and right legs worked in frantic unity to move her on her back which only worked for a brief second.
Then he let go, and she stopped resisting, and they stood face-to-face for a few minutes, waving their antennae around in the water, tiny body parts near their mouth trembling fast, probably to send water back through their gills if that's what they're called in shrimp as well, maybe communicating... and since then they have remained close together, not nose-to-nose anymore but within antennae-touching-distance.
Halcyon aftermath, partnership established.
Kees had never seen this in his 750-liter tank and he was amazed, starting to regret that he'd decided to part with these animals. Before he started to try to catch them, they's been so lively and fearlessly climbing the front pane of his tank, holding still in the middle to peruse the rest of the tank. Then they became reclusive until this passionate display on a tank completely new to both of them, filled with tap-fresh water.
I plan to keep these two, and at least one is already promised to a fellow shrimp-fan (not a fan shrimp) so it looks like the problem of "who wants my Macrobrachium" is sorting itself out :-)
(note july 10, 2002:) A week after the mating, the male died. He moved less over the days, occasionally shook off a snail that was under the impression that he was already dead and finally his eyes were grey and he gave of a terrible smell. Any ideas of preserving him in some way were immediately forgotten once he was out of the water. Even from the closed garbage bag he gave off a very bad odor. The female is fine, I refreshed 95% of the water.
Later note: the tank broke, but I could save the female and two other females that I had by this time.
This page is linked to the home page of Frans Goddijn.
Frans Goddijn, Postbus 30196, 6803 AD Arnhem, fax +31 (0)26 3211759
Updated on Oct 23, 2002