8 Jan 2009

The Case of the Feathered Crayfish

Dear Blue Lobster:

I have a 3 year old Blue Lobster named Ozzy and he just molted and now he has these weird feather-like parasites growing off the side of him. They are an inch long. They were under his shell before he molted. They look like sea-corral and have feathered fans that look like they catch microorganisms.

I was wondering if an anti-bacteria / anti-fungal medication will work eventually. It has done nothing so far.

Do you know how to get rid of them without hurting Ozzy?

I attached a picture

Ontario, Canada

Dear Gentle Sir:

Those are no parasites, those are your crayfish's gills!

Sometimes, when a cray—or any crustacean—molts, the process goes awry. This can happen for a number of reasons, such as poor diet, improper habitat, distress, or unfavorable genetics. The process is torturous to begin with and is the most vulnerable part of any crustacean's life.

Of the many things that can go wrong during a molt, it is most common in crayfish for legs and antennae to become suppressed or mangled. Therefore it's possible in some crays for whole legs to grow underneath their shell though they remain unseen on the outside. Indeed this is how crays regenerate lost limbs.

Mismolting can result in other deformities as well, some of which can lead debilitation or death. Crayfish have been known to mismolt their tails, which means they can not escape by means of tailflapping, leaving them slow and liable to predation. A cray in a laboratory was recorded to have mismolted its eyes and spent the better part of two months blind, making it way by its sense of smell alone.

In your case, though your crayfish might look freakish and scare its other tankmates away, it will likely survive. Make sure your cray has plenty of available shelter and does not share its tank with any predacious species. If you suspect water quality being a factor in your cray's mismolt, have a batch tested at your local pet care center.

In the meantime, enjoy your cray's wonderful new plumage underwater and out of the air until the next time it molts, when the gills will hopefully become enshelled again.