Because a good start is critical to the long-term growth and survivability of the fish and because fish are most susceptible to disease and mishandling during the early-rearing stages, it is imperative that you utilize your best water in your hatchery system. Ideally, hatchery systems should be flow-thru and utilize cold, pathogen-free water. The ideal hatching temperature for Rainbow trout is 8 - 12°C (~46 - 54°F), though temperatures ranging from 4 - 18°C (~39 - 64°F) are ok if proper precautions are taken. A strict bio-security program should be in place in the hatchery to limit the possible introduction of disease. At a minimum, this program should include a disinfectant footbath and hand-wash, and all equipment should be reserved exclusively for hatchery use.