EVALUATION OF AN AERATION SYSTEM IN A LOADED FISH-HAULING TANK

An aeration system (three 12-V DC Fresh-Flo aerators and two Wilfley-W eber oxygen diffusers) was evaluated in a 2,650-L fish-hauling tank lo aded with 908 kg (521 g fish/L) of 23-cm-long channel catfish (Ic-talu rus punctatus) in a static test. Water quality was monitored while fis h were being loaded (21 min) and for 4 h thereafter. Dissolved oxygen (DO) dropped from above 20 to 2.2 mg/L during the first 50 min. By the end of the test, DO had risen to 8.5 mg/L (106% saturation). The pH d ropped from 7.70 to 6.70 and the temperature row from 21.5 to 23.5-deg rees-C. Total ammonia nitrogen rose from 0.7 to 12.8 mg/L during the t est but was primarily ionized; un-ionized ammonia rose from 0.015 to 0 .032 mg/L. This poor performance emphasizes the need to monitor water quality in hauling systems for various loading conditions and aeration systems.