It would be interesting to know how often fish either get caught in a low D.O. zone or know enough to seek higher D.O. I say that because I had a catfish farm manager in Mississippi tell me that when they monitored D.O. in large catfish ponds at night, if the D.O. started to crash, they would crank up the PTO paddlewheels and the catfish would immediately head for the higher D.O. even in a 20 acre pond.
