Aquarium salt and crustaceans

[Kieflow]

Is aquarium salt safe for crustaceans? I am dosing a 10 gallon with 2 tbs of salt and I want to make sure it’s safe for the dwarf Mexican crayfish I have in there. 

[FishyThoughts]

Yes, aquarium salt is safe for crustaceans. At least to an extent, salt baths/dips are very commonly used for treating parasites/diseases in them. I have done a salt dip on a shrimp, much higher concentration than you listed above. But that was a short period, few minutes. 
Is the salt for treating the crayfish, or something else in the tank? If for the crayfish I’d suggest just doing a salt bath.

[Kieflow]

@FishyThoughts it’s for a betta in my tank that has dropsy. I have a small sorority and this is the second one to get dropsy in this tank. I’m don’t know what’s causing it so I’m trying salt and stress coat. If that doesn’t work I will probably break up the sorority. 

[FishyThoughts]

I don’t know a ton about dropsy, but I didn’t think it was one of those things that was contagious. But more of a symptom of another issue with the fish.  Sorry I can’t be more helpful with this, but I don’t have experience with it. Nor do I know the effects of the salt with crustaceans for longer periods.