Supplement 2 Model of flood-related losses. A simple model for flood-related losses from fish farms was constructed based on empirical survey findings. The model greatly simplifies reality by treating stocking level or density as a proxy variable for level of investment, and thus the riskiness of a cropping decision. The model was used to derive a pay-off matrix that could be into a fish farming simulation game. The assumptions of the flood risk model will now be described. Value of harvest (Hd) at stocking density d is assumed to be directly proportional to, and double, the input costs (Cd): Hd = 2Cd In this system variable costs (for stock, feed, medication and labor or labor-opportunity) dominate costs and fixed costs (equipment or cages) have short life spans, so fixed costs were assumed to be zero or subsumed within variable costs. Profit from a crop (Pd) if no flood (f=0) is then just equal to input cost or Pd,0 = Cd if f = 0 Profits from a crop if a flood (f=1) occurs is adjusted for reduced value of harvest (1-Ld) and nonharvest related loss (k), for example, to cages or equipment, assumed to be proportional to cost: Pd,1 = 2 Cd (1-Ld) – k Cd if f=1 The fraction of harvest lost for flood was set at following values for three stocking densities (low, medium, high): Llo=0.15, Lmd=0.65, Lhi=1. The non-harvested costs was set at constant k = 1.7. The expected pay-offs for probability of flood α are then: E(Pd) = α Pd,1 + (1-α) Pd,0 The pay-off matrix for this model was calculated using above assumptions and is shown in the table in Figure 2 in the main text along with the expected pay-offs for each fixed stocking strategy across a range of flood probabilities. The values used in the actual game were derived from the standardized matrix where high stock, no flood, has a value of 1 by multiplying all entries by 100 – interpreted with farmers in units of a thousand Baht. The average expected payoff in this game with random strategies for range of probabilities from 0.1 to 0.5 is 19 (thousand) close to the observed median profit for a last harvested crop of 20 (thousand) baht.