​ Neocaridina palmata: parasites in shrimp - no color morphs

28th Jul 2019

Neocaridina palmata: parasites in shrimp - no color morphs

"N. Palmata infected with Acanthocepala" Photo courtesy of crusta10.de

Neocaridina palmata: parasites in shrimp - no color morphs

Just a short article about a fact well known in Germany, but probably unknown in the English shrimp hobby.

The orange cysts in wild-caught Neocaridina palmata were identified to be encapsuled cysts, an intermediate phase of a parasitic worm. In nature these easy to see orange cysts may play a role to attract predators. In the aquarium they are just nice to watch at, but do not seem to harm the shrimp at all. As the reproduction cycle does probably involve birds as next step, the reproductive cycle is disturbed. That is why there is none of these cysts in tank raised individuals. More exact studies are still going on. Parasites like that occur also in wild amphipods (i.e. Hyalella or Gammarus), that is why it is not recommended to use these as food for fish, unless they are captive bred.

detailed German article:
Acanthocephalus sp. in amphipods:
• Taraschewski, H. (2000)
Host-parasite interactions in Acanthocephala: a morphological approach.
Adv Parasitol. 2000;46:1-179.
• Dezfuli B.S. & L. Giari (1999)
Amphipod intermediate host of Polymorphus minutus (Acanhocephala), parasite of water birds, with notes on ultrastructure of host-parasite interface
Folia Parasitologia 46: 117-122

Neocaridina palmata and other closely related Neocaridina species like N. heteropoda are occasionally imported as "Chinese blue shrimp" etc. These types have all in common, that they are black to blue in color. However that color does not appear in the next, tank raised generation. So a genetical reason can be excluded to be unlikely. Shrimp exporters claim that these shrimp are not artificially colored. Further reasons that could cause the blue coloration could be food, only found in nature. As coloration caused by food is somewhat likely to fade away, once that special food is not fed any more, it does seem likely or at least possible that the blue color is also caused by parasites whose reproduction cycle is incomplete under normal aquarium conditions. No studies were undertaken on that matter yet.

by Andy