The effect of MnSO4 concentration and selection line on growth and condition
Large-selected fish had higher on average growth rates than small-selected fish (t=2.546, P =0.011; Figure 1A, Table S1) and fish also had lower growth rate at high concentrations compared to low concentrations (t=2.062, P =0.039; Table S1), particularly the small-selected fish (Figure 1A). The average body size at the beginning of the experiment (SL at age 70 dpf) also significantly affected growth rate (t=-16.72, P <0.001; Table S1). Generally, the smaller the fish when the experiment started, the higher the relative growth rate.
The relative condition factor at age 218 dpf was significantly affected by the interaction of the selection line and concentration (t=-1.983,P =0.023; Table S1). Large-selected fish had higher condition factor than small-selected fish in all concentrations except in 0.5 and 1.5 Mn mg L-1 (Figure 1B). Among both selection lines the condition factor was clearly lowest in the highest MnSO4 concentration compared to the other concentrations (Figure 1B). Similarly, as in the growth experiment, the size of the fish when the experiment started (at age 70 dpf) had an effect on the adult condition factor: the smaller the fish when the experiment started the higher the condition factor at the end of the experiment (t=-4.686,P <0.001; Table S1).