Public hatcheries in the United States, including facilities culturing threatened and endangered fish, are severely restricted by the lack of legally approved medicinal drugs. Oxytetracycline is a drug that is approved as a medicated feed for some uses on fish, but its use is restricted to certain fish species, to certain diseases, and to certain water temperatures.  Oxytetracycline is also approved by the Food and Drug Administration (FDA) to mark fish otoliths by immersing juvenile fish in an oxytetracycline bath.

Expanding the use of oxytetracycline-medicated feed to all freshwater fish, additional systemic bacteria, and use in all water temperatures was identified by state and federal hatcheries as an urgent need to reduce disease-related mortality and improve fish health and production efficiency at public hatcheries.

Studies required by the FDA for the use of oxytetracycline-medicated feed are being or were conducted to satisfy drug residue data requirements for all freshwater fish, animal safety data requirements for cool and warm water fish, and evaluate its potential environmental effects.  Studies are also being conducted to expand the oxytetracycline immersion label to include the control mortality in disease situations where use of oxytetracycline-medicated feed is not practical