Patience is necessary when first stocking an aquarium. It is very tempting to fully stock a beautifully set upaquarium, but it is not advisable. Purchasing a small group of fish every two weeks will serve to gradually load the system and allow essential bacteria the time required to multiply and establish (dose regularly with Cycle), biologically converting toxic nitrogenous compounds produced by fish. In a new fresh water aquarium, a gradual build up of fish to achieve 1 inch of fish per gallon is recommended. Remember, fish grow.