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Approximately seven (7) different varieties of shrimp are mentioned in reference to freshwater aquaria : Yamato Numa Ebi/Caridina spp., Ghost/Grass, Wood/Singapore, Rock/Mountain, Bumble Bee, Macrobrachium, and Neocaridina spp. These shrimp are kept primarily as detritus and/or algae consumers. Shrimp of the genus Macrobrachium, however, do not provide any use to the aquarist in general. Although they could possibly be kept as a novelty for their own sake.

In addition to these shrimp, there are other aquatic invertebrates which are often encountered by aquarists. These are: crayfish (which are harvested mainly for human consumption as are Macrobrachium shrimp), Cyclops, Daphnia, and Gammarus, (which are not true shrimp). These crustaceans are used primarily as fish food or bait. These invertebrates are described in more detail in the last section of this article.

I've put together a rough taxonomic chart of Crustacea that you can view in conjunction with this article. Just click on the button below to bring the window with the chart.

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Yamato shrimp grow to a maximum adult size of 2" head to tail (approximately 5cm). Although very tolerant of salinity and pH ranges (down to 6.0), they are very sensitive to ammonia/ammonium and heavy metal concentrations, as are most freshwater shrimp. Temperature, likewise has to be kept below 30C because they are not a tropical species.

My own experience with these shrimp suggests that these shrimp are, however, tolerant of high Nitrate levels. The NO3 levels in the tank in which I have them in can regularly be measured in or around the 25 ppm levels. I've heard that others have come to this conclusion as well, so it can't be too much of a coincidence. Mine are very lively little guys. They're constantly busy. In all fairness, though, they don't seem to really enjoy the hair algae that I put them in the tank to eat. They're very interesting none-the-less and I was glad to finally get to observe them myself. I've included a picture of one of my own caridinas at right. The picture above to the left was taken by Greg Degreef, a Canadian photographer and disk golf enthusiast! I found the picture floating around the net, but thanks to James Forgan's good eye, it is now getting the proper credit it deserves.

For another interesting article on the caridina japonica shrimp, see Ryan Stover's article.

Speaking of caridina and neocaridina species in general, Uwe Werner states that if these animals are healthy they will breed without difficulty. Males, he claims can be identified by their long swimmerets and females most easily by the presence of eggs². They do not produce many offspring and the eggs are very tiny, thus the difficulty that aquarists encounter in breeding them in captive settings.

For one Chinese Singaporean aquarist's experience with this fact, see Tow Fui's article on Breeding Yamato Numa Ebi. A European aquarist has accomplished the feat and describes his experiences in this article. The information in this second article is entirely in German, however, so you'll need a translation service or a German friend. Alta Vista has a pretty good translation service on their site, you might try it. I, myself, have been experimenting with these shrimp in hopes of successfully breeding them as well. My method was borrowed from a Sasha Twen, whose information appears at the Aquascaping Web Ring Site. Her method involves "gradually" increasing the salinity of the breeding/holding tank to 17 grams per liter. I used a gallon jar, placed in the window sill, half full of tank water. I determined that 1 US gallon is equal to 3.78 l. Since I only filled it half way, I only had 1.89 liters. I then deduced that I would need 8.5 grams of salt. I divided this nicely into 5 equal portions of 1/4 tsp measurements which I added once a day for five days after the larva were released. You'll need to remove the adult shrimp at this time.

Heather Candelaria has also written a very nice piece, hosted by Erik Oslen at the Greater Seattle Aquarium Society homepage. It's a two part series. You can find Part I here and Part II here.

One of the most distinguishing traits of the Yamato shrimp is that it is much more attractively colored than the other varieties. Their bodies are light brown to opaque with a tan stripe down their back. Additional series of broken reddish-brown lines run down their sides. They will also have two dark spots on their tail, one in each rear corner. Of additional importance to aquarists is the fact that they do not possess the large claws of some of the other shrimp species AND they are purportedly longer lived.

The REAL attraction of these shrimp is their avowed success in algae consumption, especially soft algaes. They are also rumored to eat red algaes in the absence of other foods. However, like most captive inverts they will choose fish food over algae any day and often will turn on soft leafed plants (especially soft mosses, i.e. java moss and riccia) ³ in the absence of softer algae types or fish foods. They will not, however, eat Black Brush Alage (BBA), nor can they combat spot algae on tank surfaces. They are not capable, it seems, of pulling tougher algae with their " hands". They eat algae directly with their mouths.

Several mail-order companies now sell these shrimp in the United States. One of these companies is operated by Frank Grecco who carries both caridina japonica shrimp and many more unusual varities. He can only ship in large quantities. Check out his web site HERE for more great pictures of unusual shrimp. The other company selling caridina japonica is Arizona Aquatics. They also carry excellent aquatic plants!

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Bee shrimps, as they are often referred to, are fairly small. They grow to only 1" in adulthood and grow to adulthood fairly slowly. The pictures to the right show bee shrimp and crystal red together, as well as a single crystal red shrimp. The picture to the left also shows the red and black variety together. This picture was taken by Richard Sexton from Ontario. As their common name suggests, they are marked with light black to grey stripes across their backs. The ideal requirements for keeping these shrimps are a pH less than 7.5 and clean (ammonia/ammonium free) water. Temperatures in the 22-25C range are best. A planted tank with a neutral to acidic pH would be an ideal environment.

Bee shrimp are not particularly great algae consumers; perhaps due to their small size. They do however tend to remain very active and are quite peaceful toward other tank mates. Soft mosses, flake food, and vegetable matter are favored over other food sources. Frans Goddijn suggests carrots and Mr. Suzuki (Crystal Red site) suggests boiled spinach.

To breed the Bee shrimp successfully, the aquarist needs only maintain the proper environmental conditions set forth above. Clean water being of utmost importance. Bee shrimp can reproduce on a monthly basis if cared for properly. The life span of the average Bee shrimp is only 15 months and it generally takes about 6 months to attain adult size⁵. I am not certain if the shrimps must have attained adult size before they will begin to produce offspring or whether their reproductive potential begins at an earlier stage.

Another great resource for information on caridina species, especially those native to Australia, can be found in this article by Adrian Tappin, webmaster of the Home of the Rainbowfish site. You can check out the article Here. This is an excellently written piece with very nice photos of the species discussed. This article initially appeared in "In-Stream", a newsletter of the ANGFA, an Australian Aquarium organization.

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The genera Caridina and Neocaridina belong to the family Atyidae. The family Atyidae contains 15 genera with 160 species with representatives from Asia, South America, and Africa. 120 of these species belong to the Caridina group. Requirements for the care of shrimp from either of these genera are very similar. Low dissolved metals and ammonium/ia, moderate to low pH and warm temperatures should be the norm with any of the different varieties.

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Wood/Singapore shrimp are described as being tan to pinkish with dark markings on their body area just behind the eyes. A darker stripe runs the length of the back. The picture at the left was taken from BARRON'S AQUARIUM FISH, 1992 and refers to Atyopsis moluccensis as the Brine shrimp. Uwe Werner reports that these shrimp are able to change their color according to mood or their surroundings. Another report states that dominant individuals will take on a bright orange coloration⁸. Werner describes other Atyopsis species whose tail fans also possess a yellow outlining. The information that I've gathered suggests that they reach an adult size of approximately 3 inches so can be considerably larger than the other shrimps already discussed. They tend to be territorial, but no reports of aggression toward tank mates have been reported thus far.

Wood/Singapore shrimp are ideal representatives of the Atyidae family. Distinguishing features are " a brush-like pilosity of the pairs of the claw carrying legs and the more or less developed tendency within this genera of a reduced rostrum"⁹. Shrimp in this genus have developed specialized feeding apparatus. The Wood/Singapore shrimp is a filter feeding shrimp and has two pair of specialized webbed, fan-like, appendages instead of claws. They use these to filter algae and microorganisms from the water, effectively acting as a biochemical filtration system! They are very interesting to observe. It is a shame that they too are not so readily available in the Western Hemisphere.

These are a tropical species so should be able to handle temperatures in the higher ranges. In nature they live in flowing waters, so water quality needs to be strictly adhered to in the aquarium. Oxygen content being of utmost importance. Alkalinity and salinity ranges could not be determined, though ranges closer to neutral and moderate would more than likely suffice. Breeding information, likewise, was scarce. It is likely that the young larvae need food much smaller than that typically offered. Planktonic microorganisms found in algae or marine waters would probably be a wise choice. Perhaps a breeding aquarium filled with unicellular algae could be used to rear the young shrimp?

A species similar to A. moluccensis is A. anaspides pictured here in a preserved form.

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Many Atya specie shrimp were discovered by Uwe Werner in Central and South America. His new AquaLog book SHRIMPS, CRAYFISHES, AND CRABS, in the Freshwater Aquarium is a valuable source of information and I highly recommend it.

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Palaeomonetes are a hardy shrimp, tolerant of warmer temperatures¹¹. They are excellent scavengers and fair consumers of soft algaes, although they prefer fish (flake especially) food. These shrimp grow to an adult size of approximately 5 cm and are not particularly long lived (1-1 1/2 years at most) nor do they grow to adulthood very quickly. Most shrimp in this genus appear as slightly translucent to white; the contents of their stomachs being visible. They have ten pairs of legs, the front two pairs ending in small claws. Most also will have a small yellow - orange dot in each corner of their tail, as the shrimp in the picture at the left represents.

They have been accused of catching small fishes and fry (?). My experience, however, leads me to believe otherwise. I would guess that the fish catching shrimps probably belong to the genus Macrobrachium (which is described in more detail below). The small size of the Palaeomonetes shrimp doesn't suggest that it would be very adept at catching any fish other than the very smallest of fry. Exceptions are however the rule! One hobbyist noted in an email that he had observed his ghost shrimp actively attack seemingly healthy fish, during a period of increased temperature. His conclusion was that the shrimp become more aggressive in higher temperatures.

The Palaeomonetes group can be effectively divided into two categories; brackish and freshwater. The use of the common names is often quite confusing, so for the purposes of this article I shall use only the scientific names in this section. ¹². Palaeomonetes kadakensis or paludosus shrimp are found in predominantly freshwater systems. While Palaeomonetes pugio or vulgaris shrimp are found in brackish and/or marine waters and cannot tolerate extended exposure to fresh water. These differences, however, do not affect their physical descriptions. They do, though, have an impact on the environmental and reproductive requirements and/or habits of the two varieties. The different pH and saline needs of the two should be evident according to their natural locale. P. kada/paludosus, being primarily freshwater inhabitants, are more tolerant than the brackish species of lower pH and salinity ranges. The brackish water species may indeed benefit from the addition of iodide salts, similarly to the needs of other brackish tank inhabitants, i.e. gobies, mollies, and monos. However, the average hobbyist is not likely to be able to distinguish between the two varieties at first glance.

Reproduction traits are what most distinguish the purely freshwater species from the brackish species. Most brackish or marine shrimps produce planktonic larvae which are very difficult to raise. A tank of green algae or a brackish water environment with plenty of microorganisms for the planktonic young to feed on would be ideal. True freshwater shrimps raise the embryos from beneath their swimmerets (legs) until they are fairly well developed and able to fend for themselves. Freshwater shrimp young will resemble the adult shrimp, only much smaller. Liquid invertebrate food, microfoods, minute algae, and/or baby brine shrimp are excellent first foods. The parent should be moved ASAP. Larvae should be free swimming for 1-2 weeks depending on temperature, then will settle down/out ¹³.

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A crustacean enthusiast from the eastern United States has developed a blue-ish strain of crayfish which I had the opportunity to observe last year (2000). I include his own description of them below with permission.
The biology of these crayfish is generally the same as most crayfish species. They have elongated type pinchers as opposed to the short stumpy pinchers of some species. This would seem to indicate that they include some plant material (algae, detritus) in their diet. They do enjoy some animal material in their diet but are too small to represent much of a threat to any healthy fish. In the opinion of the breeder, they make a great scavenger in the planted aquarium. He attests that most fish will be more of a danger to these crayfish so it is important to only stock them with small inoffensive fish. Likewise, he states that they go well with small tetra's (cardinal tetras, rummynose). Catfish, however, should be avoided as tank mates except for glass cats, debawi cats, or other small non-preditory catfish. The Latin or scientific identification for this crayfish cannot be discerned because it is several generations from the wild and is almost certainly a hybrid of two or more species. The natural coloration has been changed through selective breeding to the point that they don't resemble any species I can find illustrations of. Maximum size is about two inches. The ones that I observed were well below this maximum. They move around rather well after acclimatized and are both blueish in color and brown, varying from individual to individual.

On breeding the dwarf crayfish, the breeder has the following to say: Gestation depends on the temperture, 30 days is about normal. Dwarf crayfish aren't too bad about eating their young. All ages can be kept together as long as enough hiding places are provided. He reccommends small flat rocks tumbled together and 1/2" CPVC pipe cut into 2" lengths.
He feeds his frozen brine shrimp, and chopped earth worms to induce spawning and notes that they will breed faster under continuos lighting, 24/7

If you'd like to purchase some of these dwarf varities, they are being sold at crayfish. Jonah's Aquarium...Contents

S. Hieber from the Aquatic Plants Mailing List adds these comments concerning shrimp in general...
...shrimp are arthropods (like lobsters and ants), so their exoskeletons are chitinous not calcium carbonate like gastropods (e.g., snails and oysters). Chitin is A nitrogen-containing polysaccharide.

Want to learn more about Crustaceans? Join the Crustacean Mailing List. Simply write SUBSCRIBE CRUST-L in the body of a message to MAJORDOMO@VIMS.EDU

Additionally, I would like to thank all the individuals who replied to the various requests for information from myself and from others, and who offered their time in providing clarification and personal insights on many of the vague points surrounding many of the shrimp species outlined above. Thanks again to Dr.s Fisher and Wang for their help in proofing the draft copies of this article and for their additional comments.

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