JBL Sansibar Dark is a natural substrate for any aquarium. JBL Sansibar Dark is a fine, rounded dark sand of volcanic origin. It is gentle on the sensitive barbels of bottom-feeding fish such as cory catfish and loaches. The black gravel prevents light reflections. It makes easily frightened fish feel visibly more comfortable and display their full natural brillant colours. JBL Sansibar is ideal for plant care. The fine grain size and dense layering prevent sludge and other debris from seeping in, thereby preventing decay processes which could hamper plant growth. JBL Sansibar Dark does not release hardness-producing substances or undesired silicates into the aquarium. Grain size: 0.2 - 0.5 mm.