Copepods: a natural food for fry

Copepods provide part of the natural first diet for fish fry at the next larger size. A common European copepod species, Cyclops albidus, stood as a type for all these minute crustaceans of the plankton, which were refered to as "Cyclops" by an older generation of fishkeepers. It's a telling name, for they do have a single central eye like the mythological giants imagined by the Greeks.
 
Copepods play a central role in the freshwater food web, for most of them are minute filter-feeding carnivores that concentrate the nutrition values from microscopic organisms, only to be preyed upon in turn by fry or small fish. They are among the few organisms in the freshwater plankton large enough to appear to the naked eye.
 
Culturing copepods. Copepods are universal in well-established planted aquaria, where tetras pick at them, but I didn't know a technique of creating a dependable dense culture of them for feeding young fishes, until McDaphnia clued me in: "If some Cyclops are present in the corners of a daphnia culture, you can turn that into a cyclops culture that is very productive. The presence of the cyclops probably indicates that the pH of the Daphnia culture has been dropping, so let it drop a little more, either by adding lower pH water, or by reducing water changes. Increase the amount of food (except green water) given to this culture so that some of the food produces a bacterial bloom. This should convert the culture to a cyclops culture, and the daphnia will disappear, or nearly so. One disadvantage of a cyclops culture is that there is a distinctive and unpleasant odor to cyclops. Exactly where it comes from I don't know, the cyclops themselves or their by-products. However I can tell you that those you share any dwelling attached to the fish room with, will notice this odor." Hmm. Bacteria breath?