Amanos are a wonderful algae eaters, and unlike some species of shrimp, Amanos can adapt and thrive in a wide range of water parameters.
It’s easy to see why they’re so popular.
And in this guide, I’m going to share with you info about their anatomy and biology, what you need to set up your own tank, and your tank’s water parameters.
Amano Shrimp Care Overview
Scientific name: Caridina multidentata (formerly Caridina japonica)
Care level: medium
Minimum Tank size: 10 gallons (40 liters)
Life span: 3 years (sometimes more!)
Size: 2-3 inches (5-7.5 centimeters)
Temperament: extremely peaceful
Amano Shrimp: Appearance, Anatomy, Biology
Let’s dive into what amano shrimp are.
Amano shrimp are kind of drab in comparison to their cousins, the bee shrimps. Amanos haven’t been selectively bred for color so they appear exactly like they did in the wild.
Their bodies are mostly translucent and covered with tiny brownish speckles with lines of darker speckles that run in lines from head to tail.
In the wild, this coloration helps them blend in with their environment and avoid predators looking for a tasty snack.
Shrimp are invertebrates and lack an internal skeletal structure. Instead, they have a hard, clear shell that covers the outside of their bodies.
Their bodies are divided into two main sections: cephalothorax and abdomen.
The front half of the body is taken up by the cephalothorax, which means “head-chest.” It’s covered by a solid piece of shell that protects the shrimp’s head and most of its vital organs, like the heart, brain, stomach and reproductive system.
An Amano’s head comes to a sharp point, called the rostrum, that gives it the distinctive head shape of all shrimp and lobsters. From either side of the rostrum, the eyes poke out on movable stalks that let the shrimp look around for predators without moving and giving away their position.
Amanos also have two pairs of whiplike antennae that emerge from the front of the head. The antennae are sense organs they use to help them navigate their surroundings.
At the bottom of the carapace, emerge two different kinds of legs.
Closest to the mouth are three pairs of maxillipeds, really tiny legs that only function to transport food to the shrimp’s mouth.
Behind these are five pairs of pereiopods, the shrimp’s “walking legs” that allow them to cling to and crawl across surfaces. They also use these to scrape algae off of surfaces.
After the cephalothorax comes the abdomen. This section houses the big muscles of the shrimp’s tail that let it shoot backwards away from danger.
Unlike the cephalothorax, that is covered by one solid piece of shell, the abdomen is covered by six overlapping plates that allow for movement.
Underneath the abdomen, you’ll find five pairs of pleopods, the shrimp’s “swimming legs.” These let the shrimp swim forward. The females also use these legs to hold and fan their eggs underneath their bellies until the eggs are ready to hatch.
Finally, at the end of the abdomen, comes the shrimp’s distinctive fan-shaped tail. The central point is the telson. On either side of the telson, are the endopods and exopods, small plates of shell that form the rest of the fan shape.
This fantail acts like a paddle and helps the shrimp swim away from danger more quickly.
It’s fairly easy to tell the difference between male and female Amano shrimp.
First off, females will be slightly bigger than males.
Second, you have to look at the rows of speckles that run down their bodies, specifically, the second row from the bottom.
In females, this row will be made up of long, irregular speckles, often described as “dashes.” This stripe of speckles looks kind of messy and disorderly.
In males, this row features perfectly circular speckles that are evenly spaced. They look as if they were precisely measured and painted on, much neater than the females.
Pro Tip: While sexing Amano shrimp is relatively easy, breeding them is NOT. Their eggs will only hatch in brackish water and the larvae need to be raised in saltwater, transitioned to brackish water and then transitioned again to freshwater.
And yes, that’s just as difficult as it sounds. So don’t get your heart set on breeding them unless you want to make a huge commitment.
Amanos pretty much do one thing, all day, every day: EAT. They will constantly graze along surfaces in the tank, scraping algae off of plants, decor and substrate and feeding it into their mouths.
As long as there’s plenty of food in the tank, they will peacefully munch and not really bother anyone.
When food is dropped into the tank, they will rush to it. If they can, they’ll snatch pieces of food, like pellets, and swim off to hide and eat it.
So, they’re not real big on sharing.
In the Wild
Amano shrimp are native to freshwater rivers and streams in Taiwan, Japan and the Ryukyu Islands.
Amanos are voracious scavengers that are an essential part of their ecosystem’s clean up crew. They crawl along the bottom, feeding on algae, aufwuchs, decaying plant matter, even dead fish and invertebrates they come across.
You would think that these little guys come from tropical environments, but their native waters often have temperatures down into the mid 60s (around 18°C).
As adults, they live their entire lives in freshwater. They release fertilized eggs into the river’s current, which carries the eggs to brackish water.
The eggs hatch into free-swimming larvae in this saltier water. The larvae continue to travel with the current until they are swept out to sea.
As they change from larvae to shrimplets, they begin to migrate back up into freshwater rivers and streams where they will live out their adult lives and produce young of their own.
Molting is just a part of life when you’re a shrimp.
As they grow, their hard outer shell can’t expand with the rest of their body.
So, they need to get rid of their old shell in order for a newer and larger one to grow in its place.
As a shrimp’s body prepares to molt, the old shell starts to loosen up and eventually becomes mostly detached from the muscle underneath.
The shrimp then curls its tail underneath its body repeatedly until the shell cracks in half where the cephalothorax meets the abdomen.
The front half of the body is carefully pulled free of the old shell. Once the cephalothorax is out, the shrimp flicks its body backwards to break the abdomen free from the rest of the old shell.
After a molt, it takes several days for the new shell to finish forming and harden up. This makes the shrimp extremely vulnerable, so they will usually hide until the shell is done stiffening up.
Amanos, and other ornamental shrimp, can have issues with molting if they’re kept in the wrong water parameters. Each species has its own needs when it comes to the general hardness of the water (how much calcium and magnesium is dissolved in the water) as well as the amount of calcium in their diets.
Like all shrimp, if an Amano cannot molt properly, it will die. It’s important to ensure you provide enough calcium in the water and as part of the shrimp’s diet.
Setting Up an Amano Shrimp Tank
I’m now going to take you through the process of setting up your own Amano shrimp tank.
Despite their small size, I don’t recommend that you put Amano shrimp in anything under a 10 gallon (38 liter) tank.
They need a lot of surface area to graze on and smaller tanks just don’t have enough room.
Also, in the wild, Amanos shoal together by the hundreds, so it’s better to keep them in a group of at least five to better mimic their natural environment.
The absolute best filtration to use with Amano shrimp is a sponge filter.
Sponge filters provide both mechanical and biological filtration for your tank. They trap lots of gunk and waste that’s floating around in the water column and they are the perfect home for the beneficial bacteria your tank needs to be healthy.
Shrimp love to cling to a sponge filter and eat all the gross stuff trapped there. A gooey sponge filter is pretty much an Amano all-you-can-eat buffet.
If you can’t, or just don’t want to add a sponge filter, you should at least add a sponge pre-filter to your existing filter intake.
It’s basically just a sleeve made of really porous sponge that goes over your intake. This blocks shrimp from getting sucked into the filter.
As a bonus, it provides more surface area for beneficial bacteria to grow on. It will also trap solid waste and keep it out of your filter. Your shrimp will happily graze on it, too!
I’d really recommend a high quality, full spectrum light for Amano shrimp.
It’s not that the shrimp themselves need it, or really even care, but they will benefit from the healthy, vibrant plants and green algaes that grow because of the robust lighting.
Amano shrimp come from waters that can be quite cool. They will happily live in water that ranges from 65°-85°F (18°-29°C).
You may not even need to heat your tank. As long as your room temperatures don’t dip below 65°F, a heater isn’t strictly necessary.
But, for other cold water species, like White Cloud Mountain minnows, you can skip the heater if you want.
Amano shrimp don’t really have any kind of substrate requirements. They are just fine with sand, gravel or a plant substrate.
I would recommend, however, that you be cautious using a planted substrate that reduces your pH.
If your tap water has a high pH, GH and KH, no big deal.
But, if your tap water is already soft, a pH reducing substrate could really make your water much more acidic. In that case, you may need to add extra calcium, magnesium or bicarbonate to bring up the pH GH and KH.
Plants and Decor
These little guys really appreciate a heavily planted tank. Amanos love to graze along plant leaves and eat up any old growth that has started to break down.
They also need some little hidey holes to retreat to after they molt. Shrimp are very vulnerable while their new shell is growing in and this makes them very nervous and reclusive.
After a molt, shrimp will feel much more secure if they can lay low behind some tall plants or behind some driftwood for a few days.
Water Parameters for Amano Shrimp
Temperature: 65°-85°F (18°-29°C)
Nitrate: <30 ppm
GH: 6-8 dGH (100-133 ppm)
KH: 4-10 dKH (71.5-179 ppm)
The biggest part of maintaining the water parameters in your tank is establishing a healthy nitrogen cycle.
Just in case you’re not familiar with this, let’s go over it briefly.
Any kind of livestock in your tank, whether they’re fish or invertebrates, put off waste into the water.
This waste sinks to the bottom of the tank and starts to break down. As it rots, it puts off ammonia (NH3). This is a major problem since ammonia, even in small amounts, is toxic to aquatic creatures.
All it takes is 0.25 parts per million(ppm) to start stressing fish. If it rises to 1 ppm, many species of fish and invertebrates will start to die off.
Left unchecked, waste in the aquarium will just keep putting off ammonia until it builds up and turns the tank water into toxic soup.
Seriously, no good.
Lucky for us, this is where the nitrogen cycle comes into play and stops our tanks from being toxic waste dumps.
Inside our filters there are huge numbers of beneficial bacteria that transform and detoxify ammonia.
One kind of bacteria eats ammonia and puts off something called nitrite (NO2 -1). However, nitrite is also very toxic to aquatic creatures.
But, there is a second kind of bacteria that will eat the nitrite and change it into nitrate (NO3-).
Nitrate is much less toxic and can be left to build up in the tank in between weekly water changes.
But, there’s a catch. (There’s always a catch, right?)
The bacteria don’t just show up instantly. And there is no product that can just add them to the tank.
Pro Tip: By setting up the right conditions in the tank, and being patient, you can establish a healthy nitrogen cycle in your aquarium that will make it safe for fish and invertebrates.
Check out this article that will take you through the steps for a fishless cycle.
It is extremely important that amano shrimp are only introduced into an aquarium with a well established nitrogen cycle. They are very sensitive to ammonia and nitrite, much more so than fish.
Amanos are not a species that can ride out a “fish in” cycle. They need a well established tank with stable water parameters.
Also, since they are an algae-eating species, plopping them in a brand new tank is not ideal.
They’ll do much better in a tank that has plenty of algae, aufwuchs and other tasty gunk to graze on all day.
Feeding Amano Shrimp
Now I’ll take you through the kind of diet these little guys follow.
Amano shrimp have become so popular in the aquarium trade because of their reputation as superior algae eaters.
Don’t get me wrong, they can do a great job of cleaning up algae in a tank, even varieties other algae grazers won’t touch, like black beard algae.
They can mow through hair algae at impressive speeds.
But, they’re only good about eating algae if they’re hungry.
If there’s a bunch of tasty fish food or sinking pellets laying around, they will completely ignore the algae and eat that stuff instead.
Think about it this way, if you turned a little kid loose in a room with chocolate cake and broccoli, and tell them they can eat whatever they want, take a wild guess which one they’re going to devour and which one is going to sit there uneaten.
Shrimp are no different.
If you want them to eat more algae, cut back on how often you feed them.
What to Feed Amano Shrimp
Freshwater shrimp are primarily omnivores. So it’s good to feed them a mix of plant-based and meaty foods.
A high quality prepared shrimp food, like Omega One Shrimp and Lobster Pellets, makes a great staple diet. These pellets combine whole fish with kelp and other algae, providing balanced nutrition perfect for Amanos.
It’s also fortified with calcium, an important nutrient that shrimp need to grow healthy shells.
Amanos also appreciate blanched veggies like spinach, kale, cucumber, squash and carrots, some of which are also good sources of dietary calcium.
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When to Feed Amano Shrimp
If you’re used to feeding fish, you might think that you need to feed your shrimp every single day, but this may not be the case.
Pro Tip: It’s extremely important to not overfeed your shrimp. Uneaten food breaking down in the tank can lead to big ammonia and nitrite spikes, which are especially deadly for Amanos. In an established tank, you will probably only need to feed your shrimp 2-3 times a week.
It’s really easy to tell when your Amano shrimp need to be fed.
They will get really agitated and swim around the tank like crazy if they don’t have enough to eat.
When you see this behavior, you’ll know they’re hungry and it’s time to drop in some pellets or blanched veggies for them to eat.
But, it they’re just peacefully grazing along surfaces of the tank, they’re scraping up algae and there’s no need to add any food.
Tank Mates for Amano Shrimp
Let’s discuss some good tank mates and some not so good ones.
Good Tank Mates
Amano shrimp are very peaceful. You have to worry more about tank mates bothering them than you do about them bothering anybody else.
One thing though, they are a bigger shrimp. So if you keep them with smaller species of ornamental shrimp, like cherries, you have to make sure the Amanos don’t outcompete the smaller guys for food.
Fish species to consider:
- White cloud mountain minnows
- Zebra danios
- Celestial pearl danios
- Neon tetras
- Cardinal tetras
- Chili rasboras
- Harlequin rasboras
Basically, you want to stick with smaller, peaceful community fish.
Bad Tank Mates
Absolutely stay away from larger, aggressive fish.
Any species of fish big enough to fit an Amano in their mouths will more than likely try to eat them.
Fish to avoid at all costs:
– Jack Dempseys
– Jewel cichlids
- Knife fish
- Silver dollars
- Goldfish (they’ll eat whatever doesn’t eat them first)
If it’s big, aggressive or semi-aggressive, you can pretty much count on the fact that it will gladly eat your shrimp the first chance it gets.
So yes, the idea of Amano shrimp and a green terror might sound cool, but it will end in tragedy.
Well… for the shrimp at least. The green terror will be really happy and beg for more tasty treats.
Are Amano Shrimp Right for You?
Amanos are a wonderful algae eater that can even handle things like black beard algae that other cleaning crew critters will leave behind.
Peaceful in nature, you have to worry more about protecting them than having any issues with aggression on their side.
Unlike some species of shrimp, Amanos can adapt and thrive in a wide range of water parameters, but they do require a well cycled and established tank.
It’s easy to see why this species has become so popular. Not only are they peaceful and interesting to watch, but they’re a useful species that can help your tank look it’s best.