I can supply a daphnia starter culture for $5 if you bring your own jar, or $7 if I supply the jar. Care is simple, as they only require maintenance about once every 3 days. I feed them with a yeast solution. It is highly recommended to divide your sample into 2 or 3 separate cultures, as occasionally, the culture can die off for no apparent reason. Makes an excellent first food for axolotls (aquatic salamanders), as well as different fish and frogs. They are also known as water fleas, due to their jerky motions. It is an economical fish food, as you can keep a culture going indefinitely at little to no cost with minimal space and maintenance requirements. They can be rather expensive to order online, as shipping for live critters is expensive. I paid about $30 for my starter culture.