Although crayfish are still a relative niche pet, the number of people keeping a pet crayfish within the aquarium keeping hobby has been steadily increasing over the last decade.
With a number of crayfish keepers sharing photographs and videos of their pets on social media, we have noticed a spike in the number of people looking to add a crayfish to their tanks.
One of the most common issues that people have with their crayfish no matter their level of experience of actually keeping crayfish is due to issues with shell rot on their crayfish.
Although many of the causes of crayfish shell rot can often be avoided, we wanted to publish this article to try and help as many of our readers not only treat the shell rot on their crayfish but also avoid it occurring again in the future.
What Causes Shell Rot In Crayfish?
There are a number of different causes of shell rot in crayfish but the most common cause by far is problems with water parameters followed by the crayfish having an open wound on it.
The rest of the causes of shell rot in crayfish that we will cover below are less common than these two but still something to factor in if you are keeping crayfish.
Problems With Water Parameters
The most common cause of shell rot in crayfish is due to problems with water parameters in the tank that the crayfish is being kept in.
Although shell rot can technically be caused by any parameter being out of whack, we have found that the issues are almost always related to either high ammonia or nitrite levels and/or high pH levels.
As crayfish are very sensitive to changes in water parameters, even a slight change can trigger shell rot in crayfish if the crayfish is already weaker due to other issues.
Some issues with water parameters can turn your aquarium into a breeding tank for the various types of bacteria that cause shell rot to. This can drastically increase the chances of your crayfish developing shell rot even if it has no other issues.
An Open Wound On The Crayfish
The second most common cause of shell rot in crayfish is due to an open wound on the crayfish.
Although shell rot can technically be caused on any open wound, we have found that it is almost always related to either the crayfish being attacked by another tankmate or any other injury that breaks the shell of the crayfish fully.
Even if the shell is only cracked and not fully broken, this can provide an entry point for bacteria to infect the crayfish and cause shell rot.
Stress And Anxiety
The third most common cause of shell rot in crayfish is stress and anxiety.
Although this may seem like a bit of an odd cause, we have found that it is one of the most common causes of shell rot in crayfish.
Crayfish are very sensitive to changes in their environment and if they are constantly being moved around or their tank is not set up correctly, this can cause a great deal of stress to the crayfish.
This stress can then lead to shell rot as the crayfish’s immune system is weakened and it becomes more susceptible to infection.
The fourth most common cause of shell rot in crayfish is poor diet.
Although shell rot can technically be caused by any nutritional deficiency, we have found that it is almost always related to a lack of calcium in the crayfish’s diet.
As crayfish shell is made up of calcium, a lack of this vital nutrient can cause shell rot as the crayfish’s shell begins to break down.
A lack of other vitamins and minerals can also cause shell rot but we have found that a lack of calcium is by far the most common issue.
Old Food And Detritus In The Tank
The fifth and final most common cause of shell rot in crayfish is old food and detritus in the tank.
Although shell rot can technically be caused by any type of contamination in the tank, we have found that it is almost always related to either old food or detritus in the tank.
The rotting food and detritus offers a breeding ground for the bad bacteria in your aquarium tank and can cause shell rot in your crayfish if they come into contact with it, especially if they have a wound on their shell.
A Heavily Stocked Or Small Tank
The sixth and final cause of shell rot in crayfish is a heavily stocked or small tank.
Although shell rot can technically be caused by any size tank, the additional stress and anxiety a crayfish can experience when kept in a heavily stock or small tank leaves it open to the other causes of shell rot in crayfish.
How Can I Tell If My Crayfish Has Shell Rot
The first and most obvious sign that your crayfish has shell rot is if you see any white, fuzzy patches on the shell of the crayfish.
These patches are usually whiter than the rest of the shell and have a slightly fuzzy appearance to them.
If you see these patches, it is important to check for any other symptoms of shell rot as well.
Other symptoms of shell rot include:-
- The crayfish losing appetite and not eating as much as usual.
- The crayfish being lethargic and not moving around as much as usual.
- The crayfish shell beginning to break down and look thinner than usual.
- The shell of the crayfish becoming soft and rubbery.
- The shell of the crayfish beginning to fall off in pieces.
If you see any of these symptoms in your crayfish, it is important to take action immediately as shell rot can be fatal if left untreated.
How Do You Fix Shell Rot On Crayfish?
You have to realize that there are no known cures for shell rot in the traditional sense of the word. When treating shell rot in crayfish, you should always try to slow the progress of the shell rot down so that your crayfish simply molts the rotting shell with various treatments being able to help achieve this.
Although Melafix is controversial when it comes to treating shell rot on crayfish, it can help in some situations and due to it being such a cheap, easy, and readily available treatment option, it can definitely be worth trying but there is still a high chance it won’t offer much benefit.
The various types of salt bath are often considered the best way to treat shell rot in crayfish by slowing its progress down until the next molt of the crayfish.
Aquarium salt can be used to treat shell rot on crayfish as it will help to dehydrate the bacteria and stop it from spreading.
The Epsom salt bath is a very popular way to treat shell rot in crayfish as it is known to be effective in many cases. There are a number of ways that you can implement an Epsom salt bath as well as a number of different ratios that you can use for the salt you actually use.
To do an Epsom salt bath, you will need to mix 2 tablespoons of Epsom salt per gallon of water. Once you have mixed the salt and water together, you will then need to place your crayfish in the saltwater for around 10-15 minutes.
Most species of crayfish are small enough to be placed in an empty 4 liter ice cream container to serve as the container for the salt bath. This allows you to maintain stready water parameters in your aquarium without having to treat your crayfish in there.
Some people use pool salt rather than Epsom salt and although both can work, pool salt can often be less effective than Epsom salt. Some people will also drop an air stone in the water to help keep it aerated during the treatment too.
We would always recommend that you setup an alarm clock to keep track of the time as leaving your crayfish in the Epsom salt bath for too long can quickly result in other issues.
Depending on how bad the shell rot is in your pet crayfish, you will probably have to repeat this process every three to four days until your crayfish either molts or the areas of the shell rot are starting to bleach.
If your crayfish molts and you can still see the shell rot on the newly formed shell, you should maintain the salt bath process until the next molt if possible to prevent the shell rot from making it through to the next shell.
How Long Does It Take A Crayfish With Shell Rot To Recover?
Shell rot on a crayfish will usually be treat within one molt cycle but in some very bad cases, it can take two molt cycles to fully remove the shell rot from your crayfish.
In extreme cases, it may take three molt cycles to try and treat the shell rot but if the condition has not been treat within two molts, something is either wrong with your process or the condition is so bad in your crayfish that it is unlikely that it will get better.
Here are some of the key points to look out for in your aquarium that can commonly cause shell rot in crayfish.
- Problems With Water Parameters
- An Open Wound On The Crayfish
- Stress And Anxiety
- Old Food And Detritus In The Tank
- A Heavily Stocked Or Small Tank
- pH Levels Being Out Of Parameters