Looking for help with possible shell rot

[sydsamaria]

I’ve had my mantis shrimp for a month and half. He had a white spot on his back when I got him, but it’s started to change color. For the first week, he accepted frozen shrimp and clams that I dipped in vitamins, but he just throws those out of his burrow. He doesn’t seem to have any interest in frozen foods anymore, but he loves to eat the snails and emerald crabs that he finds in the tank. When he throws the remains out then I will take those out.

He lives in a 30G (120L) with a damselfish (I feed him every other day), two peppermint shrimp, and various snails and crabs. I run a protein skimmer and the nature and blue Juwel lights. He has a network of PVC pipes for his burrow.

His behavior seems normal with him wondering around the tank, decorating, closing his burrow off at night, but I’m really worried about this spot on his back. He hasn’t molted since I got him. Is there anything I can do to help him? Thanks for reading.

Parameters:

Salinity 1.025

Phosphate: <.02

Nitrates 3-5

Ammonia: 0

Nitrite: 0

I do a 30-40% water change every week.

Thanks for reading and for any input.

 

[Jay Hemdal]

I've studied shell erosion on giant Japanese spider crabs. I've never found a treatment that works; we've tried bone cement with antibiotics, extra calcium in the water, antibiotics in the water, scrubbing the lesions, etc and nothing helps. The reason why is that once the crustacean lays down its shell, it stops growing. Once the bacteria/algae/fungal filaments invade the shell, there is no way for the animal to repair the damage. The ONLY thing that helps is when the animal molts, then the damage can be repaired. However, these animals have a final molt, and once that is reached, they don't molt again.

Jay

 

[rhitee93]

The reason why is that once the crustacean lays down its shell, it stops growing. Once the bacteria/algae/fungal filaments invade the shell, there is no way for the animal to repair the damage.

Interesting. Sounds like trying to fix an issue with human teeth.

 

[Stomatopods17]

Stomatopods continue molting past full growth, Roy caldwell has documented that before. Most aquatic invertebrates do but idk if theres some exceptions (my cleaner shrimp seems like it molts once a month and been full grown a year ago, lobsters are know for seemingly indefinite growth.). Shell rot in stomatopods no one really knows what exactly it is we only know two correlations; high lighting and nutrients, which leads to the belief its fungal of some kind. UV sterilization has a good correlation with reducing the likelyhood of shell disease as well.

There is no cure just like how we can't magically cure dinos overnight, its nature taking its course and preventing it from getting worse. Good water quality, low stress (the burrow part i'll get into in a moment), and good diet are your preventions to it, if it spreads close to something vital molting can be difficult and be the death of it. Usually a spot is inevitable, I can't say I've seen an o.scyllarus that hasn't eventually developed something and most caught in the field are already infected, its the location and how bad it'll get.

wdym by network of burrows? O. scyllarus can't be in a 'network' they need a U shaped completely dark burrow with rubble to close up with. They make two entrances and close them up when needing to molt, and the darkness helps with that light exposure mitigation and stress. Extra entrances means more work for the animal to properly close it up and more exposure overall, while 1 entrance makes it 'cornered' constantly.

 

[Jay Hemdal]

Stomatopods continue molting past full growth, Roy caldwell has documented that before. Most aquatic invertebrates do but idk if theres some exceptions (my cleaner shrimp seems like it molts once a month and been full grown a year ago, lobsters are know for seemingly indefinite growth.). Shell rot in stomatopods no one really knows what exactly it is we only know two correlations; high lighting and nutrients, which leads to the belief its fungal of some kind. UV sterilization has a good correlation with reducing the likelyhood of shell disease as well.

There is no cure just like how we can't magically cure dinos overnight, its nature taking its course and preventing it from getting worse. Good water quality, low stress (the burrow part i'll get into in a moment), and good diet are your preventions to it, if it spreads close to something vital molting can be difficult and be the death of it. Usually a spot is inevitable, I can't say I've seen an o.scyllarus that hasn't eventually developed something and most caught in the field are already infected, its the location and how bad it'll get.

wdym by network of burrows? O. scyllarus can't be in a 'network' they need a U shaped completely dark burrow with rubble to close up with. They make two entrances and close them up when needing to molt, and the darkness helps with that light exposure mitigation and stress. Extra entrances means more work for the animal to properly close it up and more exposure overall, while 1 entrance makes it 'cornered' constantly.

Thanks for the info, I thought they had determinate molts like horseshoe crabs do. With the American lobster and giant crabs I worked with, I thought they also had determinate growth because the molting interval was so long it essentially is that for them in captivity.
Jay

 

[twentyleagues]

What are your calc alk and mag parameters? May be all that's needed. Mantis shrimp should be kept at or near reef levels for proper "shell" health. Agree with @Stomatopods17 1 burrow 2 entrances.

 

[nmotz]

I’ve had my mantis shrimp for a month and half. He had a white spot on his back when I got him, but it’s started to change color. For the first week, he accepted frozen shrimp and clams that I dipped in vitamins, but he just throws those out of his burrow. He doesn’t seem to have any interest in frozen foods anymore, but he loves to eat the snails and emerald crabs that he finds in the tank. When he throws the remains out then I will take those out.

He lives in a 30G (120L) with a damselfish (I feed him every other day), two peppermint shrimp, and various snails and crabs. I run a protein skimmer and the nature and blue Juwel lights. He has a network of PVC pipes for his burrow.

His behavior seems normal with him wondering around the tank, decorating, closing his burrow off at night, but I’m really worried about this spot on his back. He hasn’t molted since I got him. Is there anything I can do to help him? Thanks for reading.

Parameters:

Salinity 1.025

Phosphate: <.02

Nitrates 3-5

Ammonia: 0

Nitrite: 0

I do a 30-40% water change every week.

Thanks for reading and for any input.

This looks like an old injury of some sort… it has the appearance of a lesion not a disease. It might be an attack from another mantis actually. The rest of the carapace looks pretty clean. Try soaking freeze dried shrimp or krill in Selcon, a special vitamin mixture for marine animals. Feed on the heavy side to hasten a molt. You will notice pink scar tissue if it’s an old injury.

 

[Stomatopods17]

That actually is what shell rot looks like. Its a corrosion of the shell as the bacteria/fungus/algae/parasite whatever it may be eats away at it, hence the 'rot'. It may not look brown right away but overtime you'll notice it slowly corrode into a rusty/white appearence as it gets into the flesh.

That's a pretty common spot for it too, a confrontation with another stomatopod usually is repaired in a molt (such as lost limbs, cracks, etc). They're actually pretty good about not getting injured by each other, as response to attacks is to curl up and tail face the attacker. Shell rot isn't as easily 'cured' since they eat the molt and like diatoms it'll just grow back when manually removed if it has the conditions to do so.

Here's an example of one infected with it:

Its also reasonable to think perhaps there's multiple different strains of it, it is very unknown what shell rot exactly is and caused by but whatever it may be there likely is several 'species' of it with varying severity and appearances.

 

[Derrick0580]

Maybe add iodine to encourage molting

 

[nmotz]

Maybe add iodine to encourage molting

I will say back when Dr Caldwell was active on Reef Central, he always warned against iodine for stomatopods. Dr Caldwell was a biologist at Cal Berkeley and had a lab full of mantis shrimp. He knew everything about them. Good dude, wonder how he’s doing?

 

[Stomatopods17]

I will say back when Dr Caldwell was active on Reef Central, he always warned against iodine for stomatopods. Dr Caldwell was a biologist at Cal Berkeley and had a lab full of mantis shrimp. He knew everything about them. Good dude, wonder how he’s doing?

Dr. Roy Caldwell PHD and world renowned mantis shrimp expert.

Had a neat conversation today....old buddy of mine, Dr. Roy Caldwell and I did business together for over 40 years. He is the mantis whisperer ........amazing guy and research while at the university of Berkeley in California. We met up once on conch reef in the keys, he was there looking for a...

www.reef2reef.com

Absolute legend he's still doing this at 97

___

I vaguely remember him saying something about iodine too. Idk if it was in context of iodine = bad or iodine dosing being dangerous and not worth influencing outside of salt mixes and water changes.

I can't imagine iodine is bad but in the earlier days it was very easy to accidentally kill a tank dosing it, overshooting the dose in small amounts could crash a tank. I'm not sure if that's safer to do now but I've never really payed attention to iodine adopting those beliefs its safer to just water change.

 

[nmotz]

Dr. Roy Caldwell PHD and world renowned mantis shrimp expert.

Had a neat conversation today....old buddy of mine, Dr. Roy Caldwell and I did business together for over 40 years. He is the mantis whisperer ........amazing guy and research while at the university of Berkeley in California. We met up once on conch reef in the keys, he was there looking for a...

www.reef2reef.com

Absolute legend he's still doing this at 97

___

I vaguely remember him saying something about iodine too. Idk if it was in context of iodine = bad or iodine dosing being dangerous and not worth influencing outside of salt mixes and water changes.

I can't imagine iodine is bad but in the earlier days it was very easy to accidentally kill a tank dosing it, overshooting the dose in small amounts could crash a tank. I'm not sure if that's safer to do now but I've never really payed attention to iodine adopting those beliefs its safer to just water change.

Awesome, thanks for sharing!

Yeah there are far better and safer ways to hasten a molt. I think Roy said iodine was not effective and could be harmful so it was best to avoid it. IME, heavy feeding will bring on a molt soon enough to help a mantis shrimp deal with shell rot as long as it’s a mild case.