I have 6 corydoras and two of them started darting and rubbing on anything in the aquarium and that is not normal at all. I don’t see any spots like it’s ich but maybe it’s early signs? I want to put salt in there just in case but I have a couple snails and ghost shrimp and I am not sure if it’s safe for them. What should I do? They’ve since slowed down/stopped darting but I’m still worried. Do you think they just got stressed about something for a minute?