How Often Do Crayfish Molt?

How Often Do Crayfish Molt

This site does not constitute pet medical advice, please consult a licensed veterinarian in your area for pet medical advice.

One of the natural processes of crayfish is molting or shedding the shell. You can see it if you have one of this kind in your aquarium. This process helps them to grow and develop. When crayfish grow to a certain extent, it creates a soft tissue inside the hard shell and becomes ready for shedding.

Young crayfish need almost 11 times to molt to be matured. It decreases to 4 to 5 times when they reach adulthood. Depending on the variables, they molt almost every 15 to 25 days.

The molting lasts for about one to four days approximately. It also differs from species to species.

How Often Do Crayfish Molt?

Crayfish shed their skin occasionally to develop. They tend to release their shell each fifteen to twenty five days in proper environments and conditions. The total time depends on their size too. As in smaller crayfish take less time than the bigger ones to molt.

Generally, it is seen that crayfishes take 24 hours to 3 to 4 days to complete the whole molting process.

The younger crayfish shed their shell every seven to ten days where the adult ones take more time, around thirty to forty days. As long as they are getting the proper environment, they will keep molting at their regular speed.

Basically, the whole process takes some time, but the disposal of the old hard shell is done in a minute or two.

How Do They Create A New Shell To Molt?

The rejuvenation process starts as soon as they develop the previous hard shell that they are about to shed with tissue. When it is filled, another delicate skin structures underneath the hard shell in anticipation of shedding.

When they are shedding, the hard external shell is disposed of. The arising delicate crayfish can now grow in size. The delicate bare skin then becomes solid at one point with calcium and frames another hard shell. During this short time frame, the delicate crayfish are also commercially gathered for harvesting.

When Do Crayfish Molt?

It varies according to the age, size, and species of crayfish. Besides, environmental factors play a crucial role in crayfish molting.

If you keep your crayfish with their required basic needs, your crayfish will molt every 15-25 days. But, it varies according to your crayfish size.

Several studies found that juvenile crayfish molt every 7-10 days. If your crayfish is an adult, it may take 30-40 days to molt.

Generally, crayfish molt frequently to become mature completely. Crayfish molt to shed the old, hard exoskeleton. Since the size of crayfish increases, they go through molting to grow new larger exoskeletons.

For this reason, you will not see any fully grown-up crayfish to molt. When an adult crayfish lose its limb, it’ll molt to regenerate its lost limb.

What Causes Faster Shedding?

Crawfish shedding is generally hormone controlled. The extension in crawfish size during shedding as well as the time duration between sheds can change altogether. The whole procedure can be affected by several factors, for instance, water temperature and quality, food quality, oxygen levels in the water.

There is another genetic factor. Changes are caused to a lesser extent by genetic effects.

If the conditions are favorable, crawfish tend to grow up to fifteen percent long and forty percent in weight in a long shed.

Actually, the shedding is all about growing because the hard shell act as a barrier and it needs to be removed occasionally.

Crayfish Molting Process

Crayfish molting is a difficult and sensitive process for crayfish. When crayfish start growing gradually, their old exoskeleton does not provide much room for their body growth. For this reason, they shed off their hard and old exoskeleton.

At the beginning of the molting process, their old exoskeleton splits at the top behind their neck (carapace). Through this gap, crayfish can get their body and head out from the old shell.

The entire molting process can be divided into four steps. These are-

  1. Pre-molting process (Proecdysis)
  2. Molting process (Ecdysis)
  3. Post-molting process (Metecdysis)
  4. Inter molting process (Anecdysis)


This stage is known as the pre-molting stage. In this stage, crayfish prepare themselves to shed their old exoskeleton.

You might know that the exoskeleton of crayfish consists of mainly calcium carbonate and magnesium. To start the growth of a new exoskeleton, crayfish start absorbing calcium from all potential sources that they can find.

Since the main component of an exoskeleton is calcium, crayfish start absorbing calcium from the old exoskeleton. As a result, the current exoskeleton starts to become weak in the process of reabsorbing the calcium of crayfish. Besides, these crustaceans do not leave any scope of absorbing calcium from food sources and the environment in the Proecdysis stage.


The ecdysis step is the shortest and most significant stage of crayfish molting. The entire molting process or ecdysis stage can take a few minutes to several hours. It depends on the environmental conditions and health of crayfish.

After the pre-molting stage, crayfish encourage water uptake to pump up its body. This water uptake is done through the osmosis process and drinking.

When crayfish absorb excessive amounts of water, their old exoskeleton splits in the carapace area of crayfish. Moreover, the calcium absorbed in the pre-molting stage spreads through the hemolymph of crayfish. Because of falling gastroliths into the stomach, the new exoskeleton starts to form and harden.


The Metecdysis stage is the post-molting stage of crayfish when they remain too vulnerable. Due to shedding off the exoskeleton, crayfish become soft and weak in this stage. As a result, crayfish seek hiding places to escape from predators in Metecdysis.

In the previous stage, crayfish bend their body between the carapace and abdomen. In Metecdysis, crayfish stretch their body to their full size. For this, these crustaceans tend to absorb lots of water.

Moreover, the process of regenerating and hardening the new exoskeleton begins in this stage. To form a new exoskeleton, crayfish tend to secrete chitin synthetase. At the end of this phase, a newly formed exoskeleton is found through reabsorbing calcium. This stage can last from 24 hours to 1 week.


This stage is named inter molting stage. In a word, the period from the ending of one molting to the beginning of another molting is referred to as Anecdysis. The duration of this phase varies according to the size and age of the crayfish.

Generally, the smaller crayfish require a smaller inter-molting phase. After all, these crayfish grow faster than the larger crayfish. Hence, smaller crayfish have shorter inter-molting phases and more frequent molting than larger crayfish.

What Are Ph And GH In Molting?

Keep in mind that lowering pH and growth hormone has a significant negative effect on crayfish. This severely affects the whole inner-molting spacing process and increases the mortality rate.

Total hardness (GH) is an estimate of the minerals present in the water. The mineral helps to form an exoskeleton as it is developed almost fully by calcium and magnesium.

Another thing is pH. The potential of hydrogen influences calcification. There must be a balanced pH level if you have crayfish in aquarium. At low pH, the exoskeleton of it appears to be too much flexible and moldy. It happens because of the reaction of calcium carbonate and the pH of water.

So, as a result, when molting, the outer shell will experience problems. It puts a lot of pressure on the shell because of being flexible. Takes too much time to break and can cause the crayfish to die in the process in the worst case scenario.

Again, for example, too much hard water can cause problems too. Hard water makes shells fragile and shells break easily, which also causes loss of limbs and to some extent, death.

So, it is ideal to keep the water between 4-10 ppm GH, 3-10 ppm KH, and pH 6.5 or 7.5.

How Long Does Crayfish Molting Take?

If your crayfish stay in a good condition, the entire molting can take place within 24-48 hours. Sometimes, the molting process can go on for 3-4 days.

Frequently asked questions

Q. How many stages are in molting?

Although the whole lifespan of crayfish is a continuous process of molting, for better understanding it is divided into 4 stages:

1. Proecdysis: Pre-molting Stage

2. Ecdysis: Molting Process

3. Metecdysis: Post-molting Stage

4. Anecdysis: Inter-molting Stage

The whole process is very important for crayfish to grow properly.

Q. Has my crayfish died or it is just molting?

Sometimes, yes, it is very difficult to tell which one is it. Because the shed shell looks exactly the same as a living crayfish. In that case, you have to check by taking it out. But be very careful.

Q. Why is my crayfish hiding after molting?

Your crayfish is hiding because it is freshly molted and the skin is not properly hard yet. It is protecting itself by staying away for a while until its skeleton is formed fully. So do not worry, just give it some time to catch breath.

Q. Why is my crayfish floating upside down?

Do not panic if you suddenly see your crayfish floating upside down. It is a common tendency for them at the beginning of the molting process. Just observe for some time, you will see the shedding process.

If not, immediately check if it is alive or not. Because sometimes, dead crayfish also show the same thing.


The shedding of crayfish is a stressful process for it. You need to ensure that your pet crayfish has hideouts in the aquarium. Because especially after shedding, they become vulnerable and even prone to death. These hideouts will protect your crayfish.

Moreover, it is not required to take out the shed shell from the tank when the crayfish has shed. Crayfish normally consume that and it helps them with added strength.

About Muntaseer Rahman

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