invertinverts
Arachnopeon
- Joined
- Mar 22, 2024
- Messages
- 16
I figured this would be a good place to put my shell rot post, I hope it can help some crayfish owners out there who live in places with low KH!
Shell rot, box burnt disease, brown spot, black spot, burn spot, and rust disease are all names for fungal or bacterial infection in the outer shell or exocuticle of a crayfish. These lesions look like brown or rust colored spots or patches on your crayfish. Shell rot is not common in wild crayfish populations, but it is incredibly common in captivity and many cray owners will experience it at least once.
How does shell rot work?
Shell rot is caused by bacteria or fungi taking advantage of the breached or weakened shell of the crayfish. Typically the rot kills them by complicating molting/failure to molt, or the gills rot causing respiratory failure. There are three layers of unhardened shell under the exocuticle of the crayfish and once the rot has passed all three layers it's very unlikely the cray could survive. Shell rot IS contagious to other crustaceans so if you notice any shell rot and have multiple crays together, separate them immediately.
KH (carbonate hardness): Getting the KH at a safe level is one of the most important things to help your crayfish overcome shell rot and allow them to molt and harden up correctly. If the KH is too low, the cray's shell may not harden correctly and a soft shell is the perfect habitat for these fungi and bacteria to thrive in. If the KH is too high the cray's shell may be too hard for them to break out of and they may die attempting to molt. For crayfish you'll want the KH in the tank to be in between 6-15 but this is different for every crayfish. Please look up the species of cray you have to determine the correct KH!!!!
How do I raise the KH??
Adding crushed coral, eggshells (prepared properly), cuttlebone, shrimp salts, and wonder shells can all raise the KH in your aquarium. In my experience, wonder shells raised the GH (general hardness) rapidly and didn’t raise the KH and I didn’t have any success changing any parameters with eggshells. I have not tried cuttlebone but have heard of people having success with them. I had success with crushed coral, but you have to test often and not do too many water changes which can potentially cause a spike in ammonia. The KH will rise slowly over time and when you replace some of the water it quickly drops. I personally had the most success with shrimp salts, the brand I use is called Salty Shrimp/Shrimp Mineral. It is very important that you dose whatever you use correctly!!! Continue to test the water regularly to make sure the KH doesn't rise or drop too rapidly.
But my crayfish already has shell rot... What can I do to help it?
When my cray got shell rot I did salt baths every day for about a month and he did recover. This is what I did if you're curious, but it took over a month of doing this every day and his shell rot wasn't on his main body.
8tbs aquarium salt boiled in 1.5 cups of dechlorinated water
Mix the salt water with 3 cups aquarium water
I built up over time from 1 min to 10 min dip. You have to watch very closely because the salt water can kill them so if the cray starts looking grey or falling over put him back in the tank asap. The idea with the salt bath is to let the salt kill the bacteria before it kills the animal which can be a fine line.
What causes shell rot?
- Poor water quality: Water quality is by far the most common cause of shell rot. Build up of ammonia makes crays more susceptible to shell rot, but more importantly you'll need to keep an eye on your KH levels.
-Overcrowding: Overcrowding can lead to unnaturally large bacterial populations, and with more animals in the tank the risk of scratches in the exocuticle is heightened. Just a small scratch or nick can be enough for the bacteria or fungi to root in and start eating your animal.
-Stress: Stress makes crayfish more susceptible to shell rot.
-High TDS (total dissolved solids): Total dissolved solids represents the concentration of dissolved substances in a liquid. There are several studies showing that total dissolved solids being too high can make crayfish susceptible to shell rot.
Test your water! It is vital that you test your aquarium water frequently. Ammonia, Nitrite, Nitrate, PH, GH, KH, and TDS can be easily tested at home using a liquid test kit. I use the API freshwater master test kit and a total dissolved solids meter can be ordered on amazon.
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Shell rot, box burnt disease, brown spot, black spot, burn spot, and rust disease are all names for fungal or bacterial infection in the outer shell or exocuticle of a crayfish. These lesions look like brown or rust colored spots or patches on your crayfish. Shell rot is not common in wild crayfish populations, but it is incredibly common in captivity and many cray owners will experience it at least once.
How does shell rot work?
Shell rot is caused by bacteria or fungi taking advantage of the breached or weakened shell of the crayfish. Typically the rot kills them by complicating molting/failure to molt, or the gills rot causing respiratory failure. There are three layers of unhardened shell under the exocuticle of the crayfish and once the rot has passed all three layers it's very unlikely the cray could survive. Shell rot IS contagious to other crustaceans so if you notice any shell rot and have multiple crays together, separate them immediately.
KH (carbonate hardness): Getting the KH at a safe level is one of the most important things to help your crayfish overcome shell rot and allow them to molt and harden up correctly. If the KH is too low, the cray's shell may not harden correctly and a soft shell is the perfect habitat for these fungi and bacteria to thrive in. If the KH is too high the cray's shell may be too hard for them to break out of and they may die attempting to molt. For crayfish you'll want the KH in the tank to be in between 6-15 but this is different for every crayfish. Please look up the species of cray you have to determine the correct KH!!!!
How do I raise the KH??
Adding crushed coral, eggshells (prepared properly), cuttlebone, shrimp salts, and wonder shells can all raise the KH in your aquarium. In my experience, wonder shells raised the GH (general hardness) rapidly and didn’t raise the KH and I didn’t have any success changing any parameters with eggshells. I have not tried cuttlebone but have heard of people having success with them. I had success with crushed coral, but you have to test often and not do too many water changes which can potentially cause a spike in ammonia. The KH will rise slowly over time and when you replace some of the water it quickly drops. I personally had the most success with shrimp salts, the brand I use is called Salty Shrimp/Shrimp Mineral. It is very important that you dose whatever you use correctly!!! Continue to test the water regularly to make sure the KH doesn't rise or drop too rapidly.
But my crayfish already has shell rot... What can I do to help it?
When my cray got shell rot I did salt baths every day for about a month and he did recover. This is what I did if you're curious, but it took over a month of doing this every day and his shell rot wasn't on his main body.
8tbs aquarium salt boiled in 1.5 cups of dechlorinated water
Mix the salt water with 3 cups aquarium water
I built up over time from 1 min to 10 min dip. You have to watch very closely because the salt water can kill them so if the cray starts looking grey or falling over put him back in the tank asap. The idea with the salt bath is to let the salt kill the bacteria before it kills the animal which can be a fine line.
What causes shell rot?
- Poor water quality: Water quality is by far the most common cause of shell rot. Build up of ammonia makes crays more susceptible to shell rot, but more importantly you'll need to keep an eye on your KH levels.
-Overcrowding: Overcrowding can lead to unnaturally large bacterial populations, and with more animals in the tank the risk of scratches in the exocuticle is heightened. Just a small scratch or nick can be enough for the bacteria or fungi to root in and start eating your animal.
-Stress: Stress makes crayfish more susceptible to shell rot.
-High TDS (total dissolved solids): Total dissolved solids represents the concentration of dissolved substances in a liquid. There are several studies showing that total dissolved solids being too high can make crayfish susceptible to shell rot.
Test your water! It is vital that you test your aquarium water frequently. Ammonia, Nitrite, Nitrate, PH, GH, KH, and TDS can be easily tested at home using a liquid test kit. I use the API freshwater master test kit and a total dissolved solids meter can be ordered on amazon.
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