Okay, okay. The amount of caffeine that would expose the fish to would probably kill them. But with people already using Indian Almond leaves and Maple leaves, I am led to ponder what other herbs and plant tinctures are good for aquarium darkening. Green tea? Does anybody know about what plant species are abundant in the various flood regions our fish come from? And, more importantly, is anybody using anything besides Maple leaves and Indian Almond leaves in their darkwater set ups?