Fig. 3
Tuna tube apparatus. a Six tubes attached to an aluminium frame and placed inside a 300 L tank. Note the oxygen regulator on the bottom of the picture and the water inlet pipes at the top. b A plastic funnel positioned at the bottom of the tube, directs the water over the snout and mouth of the fish. c One of two 1500 gallon per hour bilge pumps connected to the tubes’ water system to recirculate the water from the tank to the tubes