Aquarium plant fertilizer for planted tanks without fish and fish tanks with small stocking density. Aquaflora N enriches aquarium water with nitrogen which is a macroelement of vital importance for life and development of plants. Nitrogen is an essential component of organic matter present in plants including proteins, nucleic acids, phospholipids and chlorophyll. Purely planted aquariums or fish tanks with very low stocking density often show the need to supplement water with nitrogen. Deficiencies in this element result in growth inhibition and over a longer period of time plant dieback may also take place. Aquaflora N contains nitrogen in the form of nitrates that are easily assimilated by plants and safe for fish. The preparation constitutes also the source of potassium.