API Copper Cu+ Freshwater & Saltwater Aquarium Test Kit, 90 countCopper a treatment for many parasitic infections must be monitored in an aquarium or a pond. The copper level can drop too low for the treatment to be effective, or can increase to a point that is detrimental to fish health. Copper is likely even present in your tap water. The API COPPER TEST KIT allows you to easily and accurately monitor copper levels to maintain copper based fish treatments at therapeutic levels, and tests copper levels from 0 to 4