Dear Blue Lobster:
My shrimp Arty has white spots they look like pimples i think he is embarrassed because he doesn't eat much and twitches a lot. please help if you can i want him to grow up big so i can eat him.
Dear Gentle Sir:
Your shrimp does not have acne; in fact, crustaceans are immune to that disease thanks to their tough shells. Instead, your shrimp has what is known commonly as crustacean acne or bug blight, but is known in veterinary circles as White Spot Disease.
White Spot Disease is caused by Topicalis albinus, a fungus not unrelated to the band of fungi that cause our own Athlete's Foot and ringworm. In crustaceans, the fungus grows in the soil and during the warm months releases spores into ponds, streams and lakes where they then infect crustaceans.
The fungus enters through the mouth parts or any holes or abrasions in the shell. After it has infected its host, the fungus enters a secondary life-cycle where it releases spores to the lake or stream through the crustacean's exoskeleton, where the fungus then finds its way back into the soil. The spores are the small white spots we see in our pets.
The only treatment for White Spot is copper, which kills invertebrates in high enough concentrations. The trick is avoid killing your shrimp at the same time. Begin by droppering in copper aquarium medicine a few drops at a time. Use a snail as your "canary," as it will die when the concentration is high enough to kill the fungus but before your crustaceans succumb.
Another tactic is to remove the infected crustacean from your tank, scrub it with low-grit sandpaper or pumice stone, and restore it to a fresh change of water. Some owners of large lobsters and crabs have used electric grinders as well. If the crustacean is too sick or young, however, the abrasive nature of this treatment may well tear it to pieces. Use caution when scrubbing!
One thing to keep in mind is that crustaceans with White Spot Disease are highly toxic. Never ingest one even after thorough boiling. You may catch an internal form of the fungus, a serious and potentially chronic medical condition requiring copper treatment that can result in topical patina.