Red Cherry Shrimp have quickly become the most popular freshwater invertebrate in the hobby. Their peaceful nature, bright colors, and ease to breed have led to a meteoric rise in their popularity.
Being invertebrates, Red Cherry Shrimp do not have a rigid internal skeleton as we do, but instead, have a hard external skeleton around their bodies which is called an exoskeleton. As Red Cherry Shrimp grow they have to literally pull themselves out of their old exoskeleton. This process is called molting.
Occasionally, shrimp have problems molting which usually leads to their death. In this article, I look at what the main problems are, what causes them and how to avoid the problems in the first place.
What is Molting?
As Red Cherry Shrimp grow, they are restricted by their exoskeleton. It is essentially a jacket around their entire bodies that becomes tighter and tighter as they get bigger. When the time is right, the exoskeleton will split just behind the head and the Red Cherry Shrimp will pull itself out of its old skin.
Young Red Cherry Shrimp may molt every 1 or 2 weeks, whereas older shrimp may only molt once a month.
Once the Red Sherry Shrimp have pulled themselves out of their old skin, it takes a couple of days for their new exoskeleton to fully harden up. During this time they are vulnerable, and so may choose to hide away either under rocks or in clumps of moss or plants.
Molting is also an essential part of a Red Cherry Shrimp reproduction system. When the eggs have fully developed inside the female shrimp and she is ready to have them fertilized she will molt. This molt allows her to give off pheromones which let any male Red Cherry Shrimp nearby know she is looking for a mate.
How do Red Cherry Shrimp Molt?
Once the shrimp is ready to molt its swimmerets begin to move frantically and the shrimp appears to start bobbing up and down. After a minute or two or furious movement, the shrimp essentially begins to lift itself out of its old skin.
The head and legs are first to leave the old skin, then with a strong flick of the tail, the rest of the Red Cherry Shrimp leaves the old skin which usually floats away into the water column.
After molting the shrimps’ exoskeleton is soft and the shrimp is vulnerable to attack. At this stage, many Red Cherry Shrimp will hide either beneath a pile of rocks or in a clump of live plants. It can take a few hours to a few days for the shrimp’s new body to fully harden. The actual timescale will depend on the water parameters.
How Do You Know A Shrimp is Going to Molt?
When it comes close to molting time, a Red Cherry Shrimps’ behavior changes slightly. Often the shrimp will stop eating, then appear to stand completely still as though frozen in time. They may only slightly move their antennae but otherwise remain motionless.
Red Cherry Shrimp may remain like this for a few minutes to a few hours, often dependent on water temperature.
Molting and Breeding
As mentioned above, when a female Red Cherry Shrimp is looking for a mate to fertilize her eggs, she will molt. This action releases pheromones into the water. These pheromones tell all the males within a short radius that the female is ready to release her eggs and is looking for a male to fertilize them.
What are the Most Common Problems with Molting?
At some point, every shrimp keeper will experience their shrimp having bad molts. Sadly, a bad molt almost always results in the death of the shrimp.
Almost every bad molt is the result of one of two potential problems; diet or water parameters.
We often think of Red Cherry Shrimp as simply being a clean-up crew. It is frequently suggested we use them to clean up uneaten fish food and help break down fish poop, and it is true that they will do both of these things.
However, Red Cherry Shrimp are small, but complex creatures and they need a range of vitamins and minerals in order for their bodies to function correctly.
It is important that we target feed our Red Cherry Shrimp with food that delivers the balanced diet they require. We should not expect them to survive solely on the scraps they find lying around the tank.
I have found the following foods have the right ingredients to keep Red Cherry Shrimp healthy.
I think Hikari Tropical Shrimp Cuisine is the shrimp food I feed to my shrimp the most often.
This food contains spirulina, seaweed, and alfalfa meal, all of which are natural color enhancers. The manufacturers have developed this food specifically to help promote good molting.
Shrimp Cuisine is essentially small, sinking pellets that seem extremely palatable to Red Cherry Shrimp and the price makes it very affordable.
Shrimp King Complete is a shrimp food that has been developed specifically for freshwater shrimp by the world-renowned shrimp expert Chris Lukhaup.
This food is really high quality and has some excellent ingredients. I have fed it to my shrimp a number of times, and they certainly seem to enjoy eating it.
Shrimp King Complete contains high-quality proteins and essential amino acids that promote proper shrimp growth and aid molting.
This food is a little more expensive than some others but makes an excellent addition to a shrimps diet
In my experience, algae is an essential addition to a Red Cherry Shrimps diet. Although I would not feed my shrimp exclusively on algae wafers, occasionally feeding them something like Hikari Algae Wafers brings in nutrients they might otherwise be lacking.
Whilst diet is certainly a factor in molting and molting problems, I find water parameters to be a bigger issue. Red Cherry Shrimp are hardy and can tolerate a fairly wide range of parameters. However, they do have their limits and when our water exceeds those limits it can lead to poor molting.
There are many different water parameters in our shrimp tanks we need to keep an eye on, but when it comes to shrimp with molting issues, KH and GH are the two most important.
KH (or Carbonate Hardness)
KH is the measure of the levels of carbonates and bicarbonates that are present in the aquarium water. These are often referred to as the buffering capacity of the aquarium. Buffering capacity helps prevent pH swings, and pH swings can be fatal to Red Cherry Shrimp.
The lower the KH level in an aquarium, the greater the risk the pH can quickly rise or fall. The greater the KH level, the less like it is the pH will move at all.
KH is measured in both degrees of hardness and ppm (parts per million). A KH of between 1 and 8 works well for Red Cherry Shrimp, which is the equivalent of about 17 to 145ppm.
GH (or General Hardness)
GH is a measure of how much calcium and magnesium ions are present in the aquarium water. This is often described as how hard your water is. The higher the GH, the more calcium or magnesium is present, therefore the harder the water.
GH is a measure of the levels of essential salts and minerals that are present in your shrimp tank. These salts and minerals are crucial for shrimp molting. Red Cherry Shrimp kept in tanks that have too few salts and minerals (the GH is too low) often have difficulty successfully molting, which can lead to the shrimp dying.
Red Cherry Shrimp can tolerate a fairly wide range of GH, and it is generally accepted that somewhere between 4 and 12 dGH (degrees of hardness) which is the equivalent of 70 to 210 ppm, is the ideal GH for Red Cherry Shrimp.
If you are unsure of the KH and GH of your aquarium or your tap water, consider buying a test kit. I have had good success using the API GH & KH Test kit which I just order on Amazon (check it out here)
The White Ring of Death
The white ring of death is probably the most obvious sign that a Red Cherry Shrimp is going to have a bad molt. The white ring of death is the name given when a white (or sometimes clear) band that forms around the Red Cherry Shrimps body just behind their head.
When a Red Cherry Shrimp is preparing to molt, its shell is supposed to split just behind the head. This split allows the shrimp to break its shell all the way down its back so it can pull itself out of its old exoskeleton. The white ring of death occurs when the shell slits all around the body instead. Once this happens it is almost impossible for the shrimp to escape its old body, leading to its eventual death.
Despite its name, the white ring of death does not always spell certain death for the shrimp. Sometimes the shell will still split normally and other times the shrimp does manage to escape. If you see either multiple shrimp with the ring of death, or it happens frequently in your aquarium, it is a clear sign you need to test your water.
Getting Stuck in a Molt
Sometimes a Red Cherry Shrimp just gets stuck in its molt. This can happen at the start of the molt, or as the shrimp becomes close to being fully out. Unfortunately, there isn’t a lot that can be done to help a shrimp that is stuck in its molt.
I have read reports of other shrimp keepers being able to hold the old skin open so the shrimp can escape, and still others physically helping their shrimp out of the old skin. There is no way I have the dexterity to do this, but bearing in mind the shrimp will probably die anyway, it might be something you wish to try (carefully!)