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The fathead minnow, Pimephales promelas, is widely used as a bait, forage, and research fish in the United States. A hardy and fecund fish, this species has many attributes that are excellent for culture. Unfortunately, despite the widespread use of fathead minnows in toxicity testing and thousands of resulting publications, relatively little aquaculture‐related research has been conducted in support of commercial production. On the surface, current commercial fathead minnow production practices appear much the same as those of a decade ago. However, producers continue to refine culture methods, balancing broodfish stocking rates, spawning substrate quantity, and feeding rates in an attempt to meet both losses to predators and market demand. This review examines relevant reproduction‐related studies in the fields of ecology, behavior, toxicology, and aquaculture with the goal of advancing fathead minnow culture. In fathead minnow production, relative to the culture of food fish species, reproduction is vital, more so than rapid growth or a low feed conversion ratio. Fish numbers may exceed 1 million fish/ha, while feeding rates are relatively low and in feeder fish production, growth is deliberately restrained in order to maintain fish within market sizes year‐round. Underappreciated factors identified as affecting reproduction and with implications for commercial culture include: (a) poor egg adhesion to commonly used spawning substrates, (b) egg and fry cannibalism at high fish densities, and (c) the relatively short breeding period of individual males. Results highlight the importance of selecting an appropriate broodfish stocking rate based on fish size, anticipated pond fertility, and feeding program. New methods to improve reproductive performance will likely increase costs and will need to be accompanied by thorough economic analyses.

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Standard in vitro minimum inhibitory concentrations (MICs) were determined for difloxacin and compared with the MICs of several other antimicrobials against a standardized battery of 13 gram-negative bacterial isolates associated with shrimp disease . The palatability and safety (toxicity) of difloxacin to the shrimp Penaeus vannamei were also evaluated during 15 d of medicated feeding at 1 X (100 mg/kg of feed), 2X, and 4X treatment levels to give doses of approximately 5, 10, and 20 mg difloxacin/kg body weight . A significant reduction (P < 0 .05) in difloxacin-medicated feed palatability was noted in the 2X and 4X trials . However, differences were still acceptable, because more than 80% of the feeds were consumed in both treatments relative to the control diet . Shrimp mortality rates increased with difloxacin level from 7% for the control treatment to 20% for the 4X treatment. Differences in percent survival were not significant (P > 0 .05) by the Williams test ; however, analysis of mean survival time indicated that difloxacin significantly (P < 0 .05) reduced survival time at the highest dose . Signs of animal stress, characterized by extreme lethargy, were noted in the 4X treatment . An actual therapeutic dose for difloxacin in penaeid shrimp is unknown ; however, the 1 X treatment (100-mg/kg) was acceptable with respect to both palatability and toxicity, whereas 400 mg/kg of feed or more may be unpalatable and toxic to shrimp .Shrimp raised in aquaculture have become in-

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