Amano Shrimp – Caridina japonica

Written by


Most who have owned this species swear they are the best algae eaters and tank cleaners. They are known to eat nearly every kind of algae, which is one of the reasons they are so popular.

Common Names: Yamato Shrimp, Yamato numaebi, Algae eating shrimp, Japanese swamp shrimp

Order: Decapoda

Family: Atyidae

Class: Crustacea

Genera: Caridina

Species: japonica

Origin: Yamato River (Japan), south area of Chiba and Shimane; Korea; Taiwan

Main Ecosystem: River

Salinity: Freshwater, although larvae have to be transferred to brackish or pure saltwater

Ph: 5.8-8.0

Temperature: from 59ºF / 12ºC to 82ºF / 28ºC

Hardness: 5-20ºdgH

Potential size: females up to 5.5cm/2.17”, male 3.8cm/1.5”

Temperament: With enough hiding possibilities, the Amano Shrimp is definitely not shy. They are calm and very peaceful.

Diet: Omnivore (algae, all kinds of regular fish food, frozen, flakes, tablets, dead plants, dead fish, detritus, etc.)

Care: Most who have owned this species swear they are the best algae eaters and tank cleaners. They are known to eat nearly every kind of algae, which is one of the reasons they are so popular.

In my experience, I’ve noticed that they seemingly ignore spot algae and black beard algae or it just takes them a long time as other sources state.

Make sure to provide hiding places such as plants and other decorations. Try not to place the Car. japonica in a community with large or aggressive fish; it will make them shy, or in the worst case, they will be a feast for your fish. It is always good to keep them in small groups (“small” would be depending on your tank size) that will give them the feeling of protection.

Caridina japonica is very sensitive toward ammonia, an immature/unestablished tank as well as heavy metals; especially copper.

Water Region: The Amano Shrimp stays mainly on the bottom or sits on plant leaves while cleaning the aquarium but can also be seen swimming in the open water.

Activity: Car. japonica never seems to stop eating, so you will be able to see these busy little helpers all over the place as long as they feel safe.(see “Care”).

Lifespan: about 3 years

Color: clear, glassy with 0.3mm reddish brown spots and a line on the back of the same color.

Sexing: Females are larger and plumper. They have a bigger bellies with abdominal pockets. If you get lucky you can see them in the lfs’s tank with some eggs in these pockets.

Acclimation: regular, like FW fish

Breeding: The Amano Shrimp is difficult to breed. The females produce eggs regularly and carries them for about 4-6 weeks. You can identify them as little white dots on the water surface, which twitch and swim with their head towards the substrate. To raise the larvae you will need clean, oxygen-rich water with a salinity of about 30g/l or 4oz/gal. It is helpful to have an extra tank with only indirect sunlight (larvae can eat the algae), which was cycled weeks ago and about 24 degrees Celsius warm. Oxygen will get into the tank by photosynthesis of the algae. You can experiment with an air pump, but will have to make sure it is too much movement in the tank to push the larvae against the glass. Feeding them with a few drops of fluid fry food every day will also help. After 4 weeks they will still hang upside down under the water surface but are easier to recognize. After 6 weeks they will start sitting on the bottom of the tank and after “real” shrimp will live in there (size about 0.5-0.8cm). You can now start to give them little pieces of algae pellets. During the last few weeks there have been made several pwc of about 20% each (try an artemia strainer to keep larvae from being sucked up into the gravel cleaner). After 12 weeks after hatching you will have to make pwc 4 times every five days with freshwater and after 16 weeks the little Caridina japonica can be transferred into regular freshwater. Acclimate like newly bought fish to the water of the new tank.

Comments: Make sure that you don’t use fish medications with copper, since it is poisonous for the Amano Shrimp. If the water temperature gets over 82F the shrimp will have protein clotting and go to shrimp heaven.
During the molting process they are very sensitive since their new shell is not hardened yet. I’ve heard that adding dried oak or beech leaves can help them during their molting process.

Make sure they can not escape from your tank through openings. It would
also be better to use a prefilter to keep them from climbing into the main filter.


Photo credit:

Last update: 2006-02-06 09:04
Author: Tiffi

Filed under Fish Profiles, Freshwater.