Would you use this methylene blue product?

[chrstn4o]

Someone on here gave me this company's link, I ordered the salicylic acid and saw they have MB (Methylenblau) so I added that to the order but then I realised it wasn't labelled as USP and there is no purity number given anywhere, including the certificates they have on the page. Would you use this in your fish tank or are you afraid the fishies may get some impurities, so you wouldn't risk it?