Seachem Marine Trace 500 ml.

Marine Trace™ supplies a broad range of trace elements demonstrated to be necessary for proper fish health and growth.
Unlike terrestrial animals, fish obtain nutrients from both their food and environment.
Trace elements are normally depleted by utilization, oxidation and precipitation, thus it is important to restore them on a regular basis.
Marine Trace™ contains only those elements actually demonstrated to be required by fish.

Directions: Use 1 capful (5 mL) for every 80 L (20 gallons) once or twice a week.