Fig. 1.

Schematic representation of the experimental design. At Day 0 (i.e. within 24 h of spawning), ballan wrasse eggs were collected from each of three spawning mats from three separate spawning tanks (1 g of eggs from each mat). The ten spawning tanks at the site are connected as two banks of five to separate recirculation systems (RAS), with Tanks 1 and 2 sharing the same RAS. The eggs remaining on each mat underwent surface disinfection by bathing in formalin (100 ppm) for 1 h and then bronopol (100 ppm) for 1 h, before the mats were transferred to a common holding tank connected to a third RAS. On Day 2 and Day 4, the surface disinfection steps were repeated, and the mats were returned to the common holding tank. At Day 5, a further 1 g of eggs were collected from each mat