Content:
Introduction
Material needed
Step 1: The Hatching tank
Step 2: Mating
Step 3: Green Water Culture
Step 4: Hatching
Step 5: Raising the zoes
Step 6: Back to freshwater

Introduction
The Amano Shrimp – Caridina japonica is known to be a great challenge for those trying to breed it. After many attempts and lots of reading, I finally managed to to succeed. The tough part was to learn how to do this but once figured out, breeding Amano Shrimp is quite simple. Using this method, I manage to get an average of 20 to 50 successfully mutated juveniles per attempt.

Material needed
Fortunately, breeding Amano Shrimp does not require too much material. The following is a list of all you should need.

- A small 5 to 10 gallon tank with a light - A few jars - A heater - A sponge filter - Green water culture (optional) - Aquarium salt

- A hydrometer, refractometer or salinity monitor - A light to grow the green water culture - Dark sheet of cardboard - A few Amano Shrimps

Step 1: The Hatching tank
The hatching tank is a pretty basic setup. All you need is a small tank (5 to 10 gallon) with a sponge filter, a light and a small heater to maintain its water at the same temperature as the main tank the shrimps are from. For background, I use a dark sheet of cardboard to easily see the zoes when they hatch.
Floating plants could also be added to the setup to provide hiding places.

Step 2: Mating
Your first step is to move some males and females in the hatching tank. Mating can occur in the main tank but it is much easier to work in a small tank with less plants (shrimps are not easy to catch!).
It is not easy to tell if an Amano Shrimp is a male or a female so all I do is to put 5-10 shrimps in the breeding tank and hope for the best. Chances to have at least one of each gender are quite good.

Male or female?
The males tend to be around half the size of females. Adult males are typically around 3cm long and the females are around 5-6cm. Another way to spot the difference is to look at the second row of spots along the side of the shrimp. Females have elongated spots which look more like a broken line while the males have rounder spots.

When the female is ready to mate she will release pheromones into the water and this will excite the males who will then mate with her. A couple of days after mating the female will lay the eggs and glue them onto her abdominal swimmerets. At first, the eggs are a dark green color although they grow progressively lighter as they develop. The female will keep the eggs with her for around 5 weeks after which larvae will hatch.

When you see a female carrying eggs onto here abdominal swimmerets, move all other shrimps back in the main tank.

Step 3: Green Water Culture
While you are waiting for the shrimp to mate, start a green water culture. Green water is by far the most convenient way to feed the larvae (also called zoes). Later, we will pour this culture into the tank so the lavae can feed on it.
Green water is a simple free floating algae also known as phytoplankton. It needs light and nutrients to grow. There are saltwater types and freshwater types (what you need is the saltwater types).
There is lot to say about green water culture so I’ll keep that for an other post. For now, I invite you to have a look at the following links:
The Culture of Marine Phytoplankton
Buy: Living Diatom Mixture Marine, Living

If green water cultivation is a problem, you could also try other food such as Baby Star II and Golden Pearls. Feeding around 5 times a day should be sufficient.

Step 4: Hatching
At this point, only the female with eggs should be in the tank. We moved the other shrimps back to the main tank (see step 2) because it is important to have the female hatch the larvae in a separate tank to protect the young larvae from being eaten.

The hatching usually occurs during the night and the female should be moved back to the main tank as soon as possible after hatching. The larvae are very tiny dots just slightly bigger than 1mm, floating in the water. There will be hundreds of them so they won’t be so difficult to spot.

Step 5: Raising the zoes
From now, the light has to be kept on 24/24hrs. According to what I have read on the Internet, a significant number of larvae die if you switch it off at night.

In the wild the larvae are born in freshwater streams and then washed out to sea. Later, juvenile Amano shrimp will move to a freshwater environment and will never go back to the marine environment (Adult caridina japonica do not tolerate saltwater). What we want to do is to recreate this in the breeding tank.

While Japanese studies suggest the larvae should be rise in an environment with a salinity of 17 part per thousand, many claim to have great success with a salinity of 33-34 parts per thousand. You might have to give it a few try and see what works best for you.

Prepare a few liters of seawater of four time the salinity (68 ppt or 122p/134 ppm depending what method you chose) and let it sit for 24.

About saltwater:
-Don’t use mere cooking salt. Always use a commercial salt especially made for marine aquaria. Salt ment for marine aquaria contains all the minerals ( in exactly the same proportions), that are contained in sea water and is the only salt that will recreate the same conditions as in the ocean.
-Use a hydrometer, a refractometer or a salinity monitor to adjust salt level.
-Let the freshly mixed saltwater sit for 24h before using. During that period, it is a good idea to vent it with an air pump.
-Watch out for water evaporation! As the water evaporates, the salt level goes up (you don’t want that).

When your saltwater is ready, syphon half the freshwater out of the breeding tank. Then, pour in 1/4 of green water and 1/4 of saltwater in order to obtain the desired salinity (17 or 33/34 part per thousand).
So if your breeding tank is 10 gallon: remove half the water (5 gallon), add 1/4 green water (2.5 gallon) and 1/4 saltwater (2.5 gallon).
Many breeder use a very progressive method by gradually increasing the salinity. Others say that it’s useless. I personally don’t bother with that and simply replace half the freshwater with saltwater and green water.

The larvae now have everything they need to grow: saltwater and food (green water). At this point, just sit and watch them grow until it’s time to move them back to freshwater.

Step 6: Back to freshwater
During their short stay in saltwater, they will go through some major anatomic changes:
Before metamorphosis, the zoes float upside down, barely able to swim, unable to walk on the bottom or walls, and just able to grab their food.
After metamorphosis (25 to 40 days after hatching), the young juvenile is no longer able to float in the water and look like a miniature adult that can walk and swim in straight line. The coloration went from orange/redish to greyish and transparent like the adults.

The zoes do not mutate at the same time. Those who haven’t metamorphosed still need salinity while those who have must me moved to fresh water. So every day from the 25th to the 40th you will have to catch the newly metamorphosed juvenile and move them to freshwater. The easy way to catch them is to suck them up with an air tube or a pipette.

Getting them back to fresh water is simple. I simply move the newly metamorphosed juvenile in a jar, and every day I change 50% of its water with freshwater. After 3 to 5 days, pour the jar into the main tank. If you fear your fish can eat your small shrimps, it can be preferable to put them in a separate tank first to let them mature a little more.

Once moved to freshwater, they will feed on the same food as the adult and will grow quite fast (They should reach adult size after 16 to 17 weeks).

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