Amano Shrimp Breeding Guide
Why breeding Amano shrimp (Caridina multidentata) is so hard: an amphidromous life cycle whose larvae need brackish water, with sexing, berried females and a demanding larval-rearing protocol.
Overview
The Amano shrimp, Caridina multidentata, is a larger algae-eating shrimp native to Japan, Taiwan and Korea. Unlike the cantonensis morphs, it is amphidromous: Wikipedia states that oviposition and hatching occur in freshwater, the newly hatched larvae drift to saltwater to develop as juveniles, then return to freshwater as adults. This life cycle makes it very difficult to breed in a standard home aquarium.
Reaching adult size, it typically grows to 25-35 mm and feeds primarily on algae. Wikipedia gives a temperature range of 18-28 °C and pH of 6.5-7.5 for the species.
Sexing
Females are larger than males. Wikipedia notes that females can be distinguished by a more elongated lower row of dots along the body, while males show a row of evenly spaced dots.
Conditioning
Adults condition easily in a planted freshwater tank with stable parameters and abundant algae and biofilm. Well-fed females will develop eggs readily; the difficulty lies entirely in rearing the resulting larvae, not in spawning.
- Stable freshwater tank, 18-28 °C, pH 6.5-7.5 (Wikipedia)
- Plenty of algae and biofilm plus supplemental feeding
- A separate brackish rearing tank prepared in advance
Breeding Setup
Successful breeding needs two tanks: a freshwater tank where the female carries and hatches eggs, and a dedicated brackish rearing tank for the larvae. The Shrimp Farm notes larvae tolerate a wide salinity, with one study citing 17-34 ppt (about 1.0128-1.0256 specific gravity); marine salt, not aquarium tonic salt, is used to mix it.
Spawning & Berried Females
Wikipedia describes the eggs as oval and rich in yolk. The Shrimp Farm states females typically carry the eggs for about 4-5 weeks. As the eggs near hatching, the larvae must reach brackish water promptly, because they survive only a short time in pure freshwater.
Shrimplet/Larval Care
The hatchlings are planktonic zoea, not miniature adults. They must be moved to the brackish tank and fed microscopic food such as cultured phytoplankton and the algae growing on the tank walls. The Shrimp Farm indicates the larvae develop in brackish water for roughly 30-60 days; once they metamorphose into post-larvae they are gradually returned to freshwater.
Common Challenges
The Amano is an expert-only breeding project. Larvae die quickly if they do not reach brackish water in time, the weeks-long larval feeding is demanding, and the salinity must be reduced gradually as juveniles metamorphose, per The Shrimp Farm. For most keepers Amano shrimp effectively do not reproduce in freshwater home tanks.