Abstract
Continuous measurement of dissolved oxygen concentration and temperature at two depths in the water column were needed for a 2004 field study conducted during actual harvests of channel catfish Ictalurus punctatus and for a small-scale research study conducted in 2005. In the on-farm field study, we collected data in grading nets loaded with high densities of channel catfish. The small-scale study was conducted in 0.1-acre channel catfish research ponds. Commercially available dissolved oxygen and temperature monitoring units did not meet study requirements, so we developed a free-floating data collection unit composed of state-of-the-art sensors, a data logger, and readily available materials. The data collection units proved to be durable under conditions existing in both loaded grading nets and in small research ponds.