By Aaron Guzman
There are numerous colorful and beautiful varieties of freshwater shrimp available in the hobby, but there is one species that stands alone for its industrious behavior. Caridina multidentata, also commonly known as the Amano Shrimp, is one of the most effective algae eating animals that can be kept in the freshwater aquarium.
Some Background Information on Amano Shrimp
In 2006, the Amano Shrimp was officially renamed from Caridina japonica to Caridina multidentata. Caridina japonica was originally described by De Man in 1892. However, a study conducted by the National University of Singapore, the University of the Ryukyus and the National Institute for Environmental Studies have shown that the species described by De Man is in actuality the same species that was described by William Stimpson in 1860: Caridina multidentata. This study appears in the Journal of Crustacean Biology.
Caridina multidentata has numerous names, including Amano Shrimp, Yamato Shrimp, Japanese Swamp Shrimp, Algae Shrimp, and Yamato numa-ebi (meaning Yamato Swamp Shrimp in Japanese). All of these names refer to the same hard-working algae-eating shrimp hailing from several regions of Japan, including the Yamato Swamps and the island of Kyushu, as well as parts of Korea and Thailand.
The Amano Shrimp are a relatively small shrimp, reaching a maximum size of 2 inches (5 centimeters). They are transparent save for the occasional brown, green, or ruddy red colorations that may form. The color of the shrimp will largely depend on diet. They possess a stripe that runs from the head to the tail, and the tail usually possesses several noticeable dots. They are a hardy species, capable of adjusting to a wide range of water conditions. However, breeding them poses its challenges, as the Amano Shrimp require brackish conditions.
These algae shrimp are not an aggressive species, though they are known to be very eager eaters and may out-compete other shrimp or sedentary and shy tankmates. Choose tankmates wisely for this little shrimp, because many fish enjoy the taste of shrimp, and any fish with a large enough mouth will most likely make a snack out of Caridina multidentata. Peaceful, like-minded tankmates should be housed with Amano Shrimp, and plenty of hiding spots should be provided. This is especially necessary when Amano Shrimp go through the molting process. They are extremely vulnerable during this time, and any stress can be detrimental.
The average lifespan of Caridina multidentata is 2-3 years.
Uses for Amano Shrimp in the Freshwater Aquarium
While he was not the first to discover them, Takashi Amano was the first to popularize Caradina multidentata in the hobby for their usefulness in the freshwater aquarium. Living up to their common name, Algae Shrimp excel at algae removal. They are highly valued among planted aquarium enthusiasts for their willingness to devour various forms of algae, including the ever-despised hair algae. These little shrimp will clean plants, rocks, ornaments, and even go so far as to sift through gravel or sand.
There are several types of algae that even the Amano Shrimp will avoid or simply overlook in favor of better foods. The thick, coarse algae that builds up on aquarium glass will primarily be ignored by Amano Shrimp. This algae is a dark green and usually builds up over time, growing faster and denser with greater light exposure and the presence of excess nutrients in the water. Very few aquarium residents feed on this type of algae, and it will be the responsibility of the aquarist to remove it. The best method for removal is a razor blade or scraper of some sort.
Another form of tough to tackle algae is black beard algae. This algae tends to grow in small blackish tufts along the leaves of plants or on the substrate. While Amano Shrimp will pick at this algae and feed upon it to an extent, they will nearly always consume other foods instead. It is best to manually remove this type of algae, as well as reducing light and nutrients to further control algae growth.
Amano Shrimp are also efficient scavengers and bottom feeders. Night and day they will search for food, pulling leftovers out from between rocks and off the substrate. They make a great addition to clean-up crews.
General Care of Amano Shrimp
The Amano Shrimp is easy to care for compared to many other shrimps in the hobby. Being swamp shrimp, they are hardy and capable of adapting to various water conditions. It is important to avoid extremes in any water parameters, and to keep those parameters stable.
Generally speaking, Amano shrimp should be kept in an aquarium with a stable pH between 6.5-8.0, and a temperature between 70-80 degrees Fahrenheit (21-27 degrees Celsius). As with all freshwater invertebrates, frequent partial water changes are critical for good health.
Amano shrimp are true omnivores and will accept nearly any food offered to them. Other than algae, Caridina multidentata should be offered suitable vegetable matter such as algae wafers, spirulina, and even zucchini. High quality packaged food intended for invertebrates or bottom feeders works as a good staple or supplement food. Live foods such as tubifex/bloodworms and blackworms will be greedily eaten. Newly hatched brine shrimp, daphnia, microworms, and greenwater are all excellent foods for newly hatched and small algae shrimp.
While not typical, it has been reported that Amano Shrimp will eat certain plants. These are usually delicate, fragile plants such as Riccia, Java Moss, and Glossostigma. Observe these shrimp carefully in planted aquariums and keep them well fed.
While a single specimen, or even a small group of algae shrimp can usually survive by only eating algae in the aquarium, supplementing their diet with nutritious food will help them grow to their full potential, develop healthy coloration, as well as condition them for possible breeding.
Amano shrimp are active, attractive, and useful members in a community aquarium or planted aquarium. Takashi Amano has advocated their use in the freshwater aquarium for many years now, and anyone serious about algae control and planted aquaria should take the time to research and experiment with these industrious little algae shrimp.
Photo Sources (top to bottom): Richardfabi, RoccosWelt, BS Thurner Hof
Cai Y.; Shokita S.; Satake, K. On the species of Japanese atyid shrimps (Decapoda: Caridea) described by William Stimpson (1860). Journal of Crustacean Biology, 26(3); 392-419, 2006.
Stover, Ryan. Everything About Caridina japonica. The Japanese Suiso Aquarium Network. Web. 30 March 2011.