Breeding Amano Shrimp: Why Is It So Hard, and How Is It Possible?
The Amano female in your tank is berried, the eggs are hatching, and yet there are no babies anywhere. This is not a mistake; it is simply the Amano's life story. While cherry shrimp multiply in the tank on their own, Amano young are built to spend the first weeks of their lives at sea. This article is not a breeding recipe: it explains why breeding Amanos is hard and what the people who succeed are really imitating. Once you understand the logic, the reason behind each step falls into place on its own.
First, the journey in the wild
The Amano shrimp (Caridina multidentata) lives in the coastal rivers of East Asia, above all in Japan and Taiwan. Scientists call this way of life amphidromous: the animal lives in fresh water as an adult, but its young need the sea to develop.
- The female carries her eggs under her belly; the eggs hatch in the river.
- What hatches is not a shrimp but tiny swimming larvae (zoea). The current carries them out to sea.
- At sea, the larvae feed on plankton and molt and change shape again and again over several weeks.
- Eventually they transform into small shrimp (metamorphosis), settle near the coast, and climb back upstream into the rivers.
University and prefectural government sources in Japan state this clearly: the larvae of shrimp like these survive only a few days in fresh water, and species with a long larval stage cannot keep a generation going in a tank of fresh water alone. So seeing a berried Amano in your aquarium does not mean a colony is on its way.
What does current research say?
Studies on Amano larvae largely confirm what hobbyists have worked out by trial and error over the years:
- Wide salinity tolerance: A study by Kondo, Hamasaki and Dan, published in Crustacean Research in 2021, raised the larvae of three amphidromous Caridina species at different combinations of temperature and salinity. Amano larvae were able to adapt to a wide salinity range of 17–34 ppt (17–34 parts salt per thousand). The researchers think this tolerance explains how the larvae can disperse all the way into the open sea.
- Close to seawater conditions: In a master's study at National Taiwan University (Lee, 2009), the larvae survived best at a salinity of 34 ppt and 24 °C. In the same study, a diatom (Chaetoceros) gave better results as a first food than another species of microalgae.
In short, the larvae can live in anything from "slightly salty" water to almost full-strength seawater, and, just as in the wild, they feed on microscopic algae. This wide range is also why the different salinity recommendations given in the hobby all work to some degree.
Breeding at home: imitating nature
What people who succeed at breeding Amanos do really rests on a single idea: imitating the journey from river to sea and from sea back to river, using separate containers. The logic of each stage comes from its counterpart in the wild.
| In the wild | Aquarium counterpart | Why? |
|---|---|---|
| Adults live and mate in the river | Female and male in the same freshwater tank | Adults do not need salt water; normal care is enough. |
| Larvae drift out to sea with the current | Newly hatched larvae are collected and moved into salt water | They die within a few days in fresh water; waiting means losses. |
| Larvae feed on plankton at sea | The container has microscopic algae and diatoms | Larvae are too small to eat normal shrimp food. |
| Metamorphosis and settling near the coast | Transformed tiny shrimp are separated out | They no longer behave like larvae but like shrimp. |
| Climbing back up the river | Salinity is lowered gradually until they are in fresh water | In the wild the transition is gradual; in the aquarium it should not be sudden either. |
1. The berried female and the hatching of the larvae
Telling male from female is easier in Amanos than in cherry shrimp; females are noticeably larger. For details, see the male or female guide. According to sources, the female carries the eggs for about 3–5 weeks.
Once the larvae hatch, they swim toward light. This fits their natural life: staying near the surface makes it easier for the current to carry them to sea. Hobbyists use this trait to collect the larvae; in a dark room, a light aimed at a single spot draws the larvae together.
2. The saltwater stage: the hardest part
How long the larval stage lasts varies by source; hobby guides generally report about 4–8 weeks, most often somewhere around 30–45 days. During this time the larvae molt many times.
There is no single right answer in the hobby about what salinity to keep them at: some sources recommend starting at brackish levels (about 15 ppt), others go straight to seawater salinity (30–35 ppt). The wide tolerance shown by the research above explains why these different approaches can work. What they have in common: salinity is tracked with a measuring instrument such as a refractometer, not by guesswork, and it is never changed suddenly.
The biggest risk the sources agree on is water quality. The larvae are very small and live in little water; excess food quickly turns into a bacterial bloom that can wipe out a whole batch at once. That is why experienced hobbyists, rather than feeding heavily, treat the algae and diatoms that form on the container's own surfaces as a food source.
3. Metamorphosis and the return to fresh water
When the larval stage ends, the animal turns into a small shrimp: it no longer drifts up and down, but swims forward like a shrimp and clings to surfaces. This is the sign that it is time to return to fresh water.
The logic here is similar to the drip acclimation we use when moving shipped shrimp into a tank, only much slower: the transition from salt water to fresh water is not made all at once, but gradually over hours or even days. In the wild, too, young shrimp move step by step from brackish water into the river.
Realistic expectations
Hobby sources and breeders say the same thing: the Amano is one of the hardest ornamental shrimp to breed. Success rates are generally low, and even experienced hobbyists sometimes lose an entire batch of larvae. That is why most Amanos on the market come from commercial facilities that can set up these conditions on a large scale.
That does not mean it is not worth trying. Breeding Amanos is one of the projects that lets you get to know shrimp's life in the wild most closely. But the goal should not be "filling the tank with Amanos," but "completing this journey, even just once." As for the Amanos in your tank, keep thinking of them as a cleanup crew; they will not multiply on their own.
Sources
- Kondo, Hamasaki and Dan (2021): Effects of temperature and salinity on larval development in three amphidromous Caridina species, Crustacean Research 50 (scientific article)
- Lee (2009): Larval rearing of Caridina multidentata, National Taiwan University (master's thesis)
- Nagasaki University: Life cycle of shrimp in the genus Caridina (academic publication; how long larvae survive in fresh water)
- Yamaguchi Prefectural Government: reproduction of freshwater shrimp (government agency; species with a long larval stage cannot sustain a generation in fresh water)
- The Shrimp Farm: Breeding Amano Shrimp (breeder guide; egg-carrying time, larvae moving toward light, metamorphosis)
- PetShrimp forum: observations on breeding Amanos (hobbyist experience)
The values and advice in this guide reflect what is widely accepted in the shrimp hobby. They can vary with the line, your water and the breeder your shrimp came from. Make changes to your tank in small steps.
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