New hobbyist- I am currently upgrading to a 20 gallon tank for my neon tetras. As I was acclimating them to the new tank I noticed that all except two of them had grayish mouths, but no cotton like or thick growths. Is this normal for neons or is this mouth rot? I suspected it was so I purchased some Maracyn II. Can I still put them into the new tank and treat them there or should I treat them in the old tank? Thanks.