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The information contained herein represents collected data and in no way is to be construed as the original work of this author. The goal in presenting this information was to provide a single comprehensive comparison of the various freshwater shrimp species mentioned in the aquarium hobby.
I wish first to thank the many individuals who helped in the development of this article by offering their advice and direction, as well as by providing some of the information found herein. A complete list of these individuals is at the end of this article.
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, B Gammarus and Daphnia (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.
Of the seven species found to be useful to the aquaria hobby, the Japanese Marsh Shrimp - better known as the Yamato Numa Ebi - is by far the most popular in the hobby. The Yamato Numa Ebi, which can be translated as Japanese Marsh or Grass Shrimp, is taxonomically identified as Caridina japonica. According to Nature Aquarium World literature, this shrimp was introduced to the aquarium hobby in 1983 by renowned aquarist and photographer, Takashi Amano 1. It is for this reason that this species is often referred to as the Amano shrimp.
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.
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.
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.
Unfortunately for North American aquarists, this species is not yet readily available in all but the coastal and near coastal states. Some report that they do ship well, so they should be more available soon in all locations. I haven't been able to test this yet, but hope to do so soon!
Another caridina species, Caridina
serrata, is also widely known in the aquaria hobby. Uwe Werner
notes that this shrimp is the most well-known, having been used in the
aquarium hobby for many years. C. serrata is of Asian descent, most
likely Hong Kong. Other shrimp hail from this area too,
i.e. C. lanceifrons, Neocaridina serrata, and Macrobrachium
hainanense4. There are several dwarf
varieties of this shrimp, most notably the shrimp commonly known as
the Bumble Bee shrimp. A hybridization of this shrimp - the Crystal Red
- is also available.
Much of the information on the Crystal Red site above is duplicated on the Caridina serrata site maintained by Frans Goddijn mentioned at the beginning of this section.
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.
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 species of shrimp, closely related to the Yamato shrimp, are classified in the Neocaridina genus. There is little to no information concerning shrimp in this genus mentioned in aquaria literature. One species that is mentioned is Neocaridina denticula, which is known in Japan as Minami numa ebi (Southern Marsh or Swamp Shrimp). Minimum requirements for the care of this species are described as a temperature between 15 and 28C and a neutral pH. These shrimp are said to attain an adult size of 3-4 cm 6.
The genii 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.
Similar to the Caridina and Neocaridina shrimps are those of the genus Atyopsis, which also belongs to the Atyidae family. The shrimp most often encountered by aquarists as either the Wood or Singapore Shrimp is from this genus. The proper designation for this variety is Atyopsis moluccensis. Other names which - based upon their descriptions - are likely synonynms are: Flower, Brine, and (Malaysian) Rainbow 7. Other aquarists have encountered shrimp of the Macrobrachium genus being offered as Rainbow shrimp as well. Common names being what they are, the proper identification of freshwater shrimp is all too often a difficult venture.
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.
Another genus or group within the Atyidae family is mentioned in aquaria literature as Attya or Atya and or Atyoida (bisculcata), several different pictures of which are listed below.
Shrimp in this group are commonly referred to as the Mountain or
Rock Shrimp and are closely related to shrimp in the Atyopsis
(Wood/Singapore) group. The shrimp pictured at the right, Paratya
compressa, may also be similar to the Rock/Mountain shrimp. Unlike
Atyopsis, these shrimp can be found in not only Asia, but in South
America and Africa. They can get quite large and generally reach an
adult size of 8-12 cm. These shrimp are true scavengers rather than
algae consumers. A large assortment of shrimp are contained in this
group so an adequate generalized description of this species could not
be discovered. Environmental information suggests that they require a
temperature in the 20-28C range and a neutral pH. They are members of
the Atyidae family, so share many of the same characteristics of the
Atyopsis shrimp, such as a brush-like covering of their claws and
(Werner provided pictures of some with "filter fans" in place of their front claws and some with "pin cushions" covering these claws. These were from both West Africa and South and Central America.)
Other information on this genus was unavailable to me.
The images below were taken from a University of Hawaii site where Atyoida bisculcata is listed as a native species.
Many Atya species 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.
More familiar, perhaps, to North American and European aquarists are the shrimp in the Palaeomonidae family.
The Palaeomonidae family contains at least four genii that might be familiar to aquarist; Macrobrachium, Palaeomonetes, Palaemon, and Leander. The last two would especially be familiar to marine aquarists. For freshwater aquarists, the genus Palaeomonetes would be familiar. Palaeomonetes shrimp are commonly referred to as either ghost, grass, or glass shrimps. Generally considered live bait foods, these shrimps/prawn10 make an interesting and useful addition to the home aquarium.
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. 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! 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.
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.
The remaining shrimp varieties mentioned in the aquarium hobby are those in the genus Macrobrachium, which also is part of the Palaeomonidae family. Macrobrachium are freshwater prawn that are often commercially raised as a food fish in many part of the world. Many different varieties exist. Macrobrachium is seldom seen in the aquarium, and then probably only as a novelty item. It gets too large for most planted aquaria and can cause damage to both plants and fish due to the existence of large claws on dominant adult males. The name macrobrachium actually means "big arm." Because of its widespread distribution and use in the food industry, many varieties of Macrobrachium are known and described as the wealth of photos listed below will attest to.
There are other invertebrates which are mentioned in the hobby as well. These are crayfish which are found in the Astacura sub-order of the Order Decapoda. This sub-order consists of five families of crayfish and/or lobsters. Another crustacea which most aquarists are familiar with are the amphipod specie Gammarus.
Daphnia and Cyclops are two others. These inverts are predominantly used as food items, either for fish or human consumption. Gammarus, also know as scuds to fishermen, are very small creatures. They measure approximately 3/4 of an inch in length (20 mm). They generally are found along shorelines among aquatic plants where they are particularly difficult to find, being semi-transparent. As far as using them in the aquarium, the only use is as a food item. Raising these small creatures requires much the same environmental conditions required to raise daphnia. A high calcium content (Kh) also needs to be maintained to ensure proper growth of their exoskeleton. Beyond this general information, little is mentioned about their existence in an aquarium.
If you know of any additional information which is not included here or which would be better representative of the subjects involved please e-mail me the information and I will be sure to include it. Thank you.
Interested in other freshwater inverts? Check out Patrick Timlin's Aquaria Links Page. Robyn Rhudy also has some interesting info on fw shrimp.
Crustaceans have the ability to conserve and store calcium. This is
important for their molting process. Some may eat their discarded
exoskeletons to reclaim lost nutrients.
Crustaceans NEED something to hold on to. They can get highly stressed from smooth/bare surfaces. This is called thigmotactic response.
of Acid Rain on the Heart rate of Ghost Shrimp An interesting
article with lots of general information.
Home of the Crystal Red Shrimp Background information on the Crystal Red Shrimp, a hybrid Bee Shrimp (Most Info in Japanese, this page in English)
Lots of Shrimp Info This site came up in many searches, but I've been unsuccessful in opening it from several different servers (so it's probably chock full o' information for those of you lucky enough to be able to open it).
British Columbia Creature Page Very Interesting Page, but mainly marine invertebrate information.
Gammarus/Scud Info Mainly for live food and fly fishing enthusiasts, but lots of great information. If interested, also try this.
California FW Shrimp A Species Protection Page.
German Aquaria Site Magazine references and shrimp taxonomy.
Want to learn more about Crustaceans? Join the Crustacean Mailing List. Simply write SUBSCRIBE CRUST-L in the body of a message to firstname.lastname@example.org
Barnes, Robert. Invertebrate Zoology. (bibliographical
information unknown). Brusca, Richard C. and Gary
J. Brusca. 1990. Invertebrates. Sinauer Associations,
Fitzpatrick, Joseph F, Jr. 1983. How to Know the Freshwater Crustacea. Wm. C. Brown Co., Dubuque, Iowa. pp 215-18.
Pennack, Robert W. 1989. Freshwater Invertebrates of the US, 3rd ed. John Wiley & Sons, NY pp 509-13.
Strenth, Ned E. 1976. A review of the systematics and zoogeography of the freshwater species of Palaemonetes. Heller of North America (Crustacea: Decapoda). Smithsonian Contributions to Zoology, no. 228, pp 27.
Thorp, J.H. and A.P. Covich. 1991. Ecology and Classification of North American Freshwater Invertebrates. Academic Press Inc., San Diego, CA.
Werner, Uwe 1998. Aqualog Special: Shrimp, Crayfishes, and Crabs in the freshwater aquarium. Dipl. Biol. Frank Schafer, Germany. pp. 6-46.
First and Foremost, I would like to thank Erik Olson and the members of the Aquatic Plants Mailing List for the information that they have gathered and maintained at both The Krib and at the APD Archive Site. It was from these sources that I gathered the brunt of the information assimilated herein. Likewise, I would like to specifically thank Dr. Shiao Y. Wang of the University of Southern Mississippi's Dept. of Biological Sciences and Dr. Mark Fisher of the Texas Parks and Wildlife Division for the wealth of information they provided, including the list of books above, and for their invaluable insights and advice.
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 Drs. Fisher and Wang for their help in proofing the draft copies of this article and for their additional comments.
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