HI, I have a male betta that I just got and I think he has" tail rot", I don`t know which med. is best for him. Please can someone explain the difference between; Maracyn, Maracyn-Two, Maracyn-Plus??...I don`t know what "gram negative and gram-positive means. I read the info. that came with the med,(I did get the Maracyn-Two). I think mabey the Maracyn Plus might be better. Also what about Betta-fix? Hope someone can help me understand the difference, and which is best for different problems. Thanks , Shimmer99