Amano shrimp (Caridina Japonica), like Yellow shrimp and Red Cherry shrimp, is an easy-to-keep shrimp for beginners. These shimps are very helpful to keep your aquarium water clear because they can eliminate most types of algae. However, it’s hard for a beginner to breed Amano shrimps, this isn’t an easy procedure that you can also know in this article.
About Amano shrimp - Caridina Japonica
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Caridina Japonica, also known as Amano shrimp or Algae Eating Shrimp is native of Japan, Korea and Taiwan where it can be found in swamps and marsh lands. It was named Amano shrimp after the aquarist Takashi Amano, who noticed their appetite for algae and introduced them in the hobby in the early 1980’s. It is now the most common shrimp present in aquariums.
Their body is transparent grayish with a tan stripe that runs the length of the back (from the head to the tail) and small broken horizontal lines/dots on their sides. The grey color becomes denser on the back. The body colour can change a little due food and water quality.
This shrimp is very useful in eliminating all types of algae, but they are not a solution against algae proliferation unless you have a large group (one or two per gallon).
Keeping Amano shrimp
They will do well in a well established aquarium. They are shy animals and prefer to be housed in large groups in tanks with plenty of aquatic plants, hiding places and peaceful fish that will not try to eat them. They can tolerate moderate levels of nitrate but regular water changes should be made to keep water quality as high as possible. They will prefer a neutral or lightly acid pH, a temperature between 60°F and 80°F.
They are known to eat algae but will also eat leftover fish food and detritus which makes them excellent cleaners. Its diet should be supplement with quality flake and/or pellet food (pellets are best).
Breeding Amano shrimp
The Amano Shrimp is known to be a great challenge for those trying to breed it. Using this method, you can get an average of 20 to 50 successfully mutated juveniles per attempt.
Preparation - Material needed
Fortunately, breeding Amano Shrimp does not require too much material. The following is a list of all you should need.
- A few Amano shrimps
- A minimum 5 gallon fish tank
- A few jars
- An small aquarium heater for the small tank
- A sponge filter
- Green water culture (optional)
- An aquarium LED light
- Aquarium salt
- A hydrometer, refractometer or salinity monitor
- Dark sheet of cardboard to create the background.
Step 1: The hatching tank
The hatching tank is a pretty basic setup. All you need is a small tank (5 to 10 gallons) 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, you can 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, gender distinction
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.
The males tend to be around half the size of females. Adult males are typically around 3 cm long and the females are around 5-6 cm. 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).
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 1 mm, 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 24/24 h. 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.
- Don’t use mere cooking salt. Always use a commercial salt especially made for marine aquarium. Salt used for marine aquarium 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, siphon 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 freshwater. 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 freshwater 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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