Harpacticoid copepods are a promising alternative food resource for larval and juvenile fishes that require live feeds in mariculture. Harpacticoids, fed alone or as a supplement, have been shown to promote faster growth than rotifers, brine shrimp, or both together. Research suggests that this is most likely related to small body size from first nauplius to adult, which favors ingestion by gape-limited fishes, and the observation that harpacticoids are naturally rich in essential fatty acids needed for marine fish growth. In addition, cultures of harpacticoids have the potential to be productive enough to be of value in mariculture because harpacticoids (a) have high reproductive output and short generation times; (b) are able to withstand variable conditions of temperature, salinity, and waste accumulation; and (c) have flexible food requirements regarding nutritional content and particle shape and size that facilitate the use of formulated feeds, monospecific algae, or both. Characteristics associated with a primarily benthic lifestyle, however, render many harpacticoid species inappropriate for large-scale mariculture applications. Most have been cultured only in the presence of substrates, complicating the harvest of early developmental stages because few harpacticoid nauplii swim. Furthermore very few species encyst or undergo diapause, requiring that high yields from mass cultures be synchronized with the birth or arrival of larval fish.