Hi all, I'm a newbie *waves*

Anyways, what I wanted to know, was in FT when I get a sick fish and I haven't used up all of either the ick/fungal treatment and I need to purchase the other one (depending on what one I have heh) It always overwrites the one I already have and doesn't fill up any of the other slots, is that because those slots are for other products or there is something wrong with my game ?

Appreciate any comments/help
Thanks!