Zooplankton have a short lifespan some being only 2 weeks long. The numbers of each specie within the overall population tend ebb and flow throughout the year. Copepods may flourish for a few days, and the rotifer and daphnia numbers seem minimal. After a few days, the opposite will probably be the case. A “good” sample will have 6 or even 8 different types of organisms present. We sell zooplankton to customers who want to inoculate their pond with a “start-up” population of these precious “bugs”.