Freshwater Shrimp
Cherry and crystal shrimp graze algae all day and breed in the tank without help. They moult as they grow, and the shed shell is left behind whole.
Photo by Atulbhats, CC BY-SA 4.0
Overview
Freshwater shrimp kept in aquariums are usually Neocaridina, small, about an inch long, and they do the work of a cleanup crew while breeding steadily on their own. A colony started with ten will usually be a colony of a hundred within a year.
They are also the most chemically sensitive thing in a freshwater tank. Copper is toxic to them in trace amounts, which puts several ordinary fish medications, some plant fertilisers and a few water conditioners out of use in a shrimp tank.
Temperament
Constantly busy and completely inoffensive. Shrimp graze biofilm off every surface, and a colony that feels secure is visible all day rather than hiding in the plants.
They have no defence against anything that wants to eat them, and most fish want to. A tank with shrimp and small fish will keep some adults and very few shrimplets. A tank with only shrimp keeps everything, which is why dedicated shrimp tanks are the usual arrangement.
Care and grooming
Algae, biofilm and blanched vegetables, plus a small prepared food a couple of times a week. A mature planted tank feeds them largely on its own.
Temperature decides how the colony behaves. A study on this species tested 24, 28 and 32 degrees C, and found 28 C, about 82 F, the optimum for culture. At 32 C, about 90 F, every female that matured and mated lost her eggs. Warmer water speeds growth and breeding and shortens life, so a stable 75 to 82 F is the useful range.
Living and exercise
Five gallons is enough, planted, with moss and leaf litter for grazing and for shrimplets to hide in. Filtration should be sponge based or guarded, because an unprotected intake removes young shrimp from the colony.
What matters far more than the tank is what goes into it. Anything copper based is out. New water goes in slowly, since shrimp respond badly to sudden changes in hardness, and a colony that has just been through one will moult and then stall for weeks.
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