Table 1. Common water quality problems in channel catfish hatchery water supplies.
Variable Desired level Problem Solution
Temperature 78-82°F too low reservoir pond for solar heating or
use water heaters
too high blend with cooler water
Dissolved oxygen 5 ppm to saturation too low vigorous aeration of incoming water
and supplemental aeration in
troughs
Carbon dioxide less than 10 ppm too high vigorous aeration (degassing) of incoming
water and supplemental
aeration in vats or troughs
Total dissolved gases delta P less than 40 mmHg too high vigorous aeration (degassing)
Calcium hardness more than 20 ppm as CaCO3
too low addition of calcium chloride to water
supply
Ammonia (un-ionized) less than 0.05 ppm NH3
-N too high do not use as a water supply; avoid
accumulation within hatchery by decreasing
fry density or increasing
water flow
Iron less than 0.5 ppm total iron too high aeration (oxidation) followed by precipitation
or sand filtration
Hydrogen sulfide less than 0.005 ppm H2S-S too high vigorous aeration (degassing) of incoming water