Pets at home treat their plants and are not safe for shrimp, i went to buy a couple of plant's and I asked if they would be ok for my shrimp tank and they said no as there plant's are treated and would kill my shrimp.
Really sorry for your losses, this happened to me a couple of weeks ago when I added plant's from a store I've always used. Now I just buy off people that i know don't treat them.
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