Dennerle Black Cones are dried cones of the black alder. The mature, dried cones of the black alder, Alnus glutinosa, contain vaulable humic and tanning substances which protect and benefit aquarium fish by natural means. Ideal for fish from tropical black water regions, wuch as discus, neons, scalares, dwarf cichlids, long-whiskering catfish, etc.Dennerle Black Cones:+ for aquarium water similar to the natural tropical aquatic habitat+ promote well-being, vitality and spawning instincts+ prevent fungal diseases and spawn mould in fish+ have a slight acidifying effect and stabilise the pH valueDosage:4-6 cones per 100 litres of aquarium water every 2-3 weeks.