“Organic” Fish

I keep putting “organic” in quotation marks because it is hard to know what it would take to consider a fish organically raised or nurtured. The basis of organic food production is control over growing conditions. But big fish eat smaller fish and migrate thousands of miles over rivers and oceans. If they end up full of methylmercury and PCBs, how can they possibly be considered organic? Fish farming also seems anything but organic. Farm-raised fish are treated with pesticides to prevent lice, and they eat pellets containing artificial colors, parts of fish and other animals, and binders and thickeners made from soybeans that could be genetically modified. How, you might want to know, could any farmed fish be labeled organic?