It does sound like she is preparing for a molt. Molts are almost always preceded by a lot of burrow construction. She will probably stop taking food a day or two prior to the molt.
Aside from good water, food and a dark burrow, I'm hesitant to recommend any other treatment. I do find that using uv sterilization seems to cut done the progression and spread of the disease and I might help with stopping reinfection if the animal molts. It does not cure or even slow a well developed case of shell disease once it has developed.
Hemisquilla californiensis is another stomatopod that is very prone to a shell disease, although it appears to be a different set of pathogens (fungus) from those that cause the brown or rust colored stain in O. scyllarus. Some people report moderate success using the diarylmethane dye "Malachite Green" to treat Hemisquilla. The standard treatment is a bath made from .25 ml /liter of Malachite Green stock solution in sea water. The stock solution is usually 1.4 g malachite green in 380 ml of water. I don't know the concentration that is usually sold commercially to aquarists to treat ich. Animals are treated for one hour every other day for three treatments. It is advised to use aeration. I have tried this with Hemisquilla and it seemed to at least slow the disease.
I must warn you, however, that this has not been tried by me on O. scyllarus, so I have no idea if it will be lethal to the animal. Also Malachite Green is a respiratory poison, teratogen, and a suspected carcinogen and should be handled with appropriate caution. Also, it is increasingly toxic to fish with increasing temperature. The Hemisquilla were treated at 15C, so perhaps a lower concentration would be necessary with an animal at 25 C. A couple of other cautions. This compound stains plastics and other surfaces green. Also, it is manufactured as an oxalate salt (green crystals) and as a zinc chloride salt (yellow crystals). The latter is toxic and should not be used.
Malachite green persists in tissues for a long time after treatment, so do not eat the animal after treatment.
Fish are sometimes treated by swabbing a malachite green solution directly on the lesions. I might be tempted to try that. For fish 100 ml/liter is used. Rinse the animal well and hold in quarantine before re-introducing the animal to its home tank.
I do not recommend these procedures. There is obvious risk involved. However, they do seem at least partially effective with Hemisquilla, so you may want to consider them.
Roy
