Why Do We Never Eat the Biggest Catfish?

You've probably wondered why a fish that can feed a whole street gets photographed, measured, and dropped back into the river. Catfish is one of the most eaten animals on earth, so why is there a size where the eating stops? It's not that the big ones are tough, muddy, or ugly. It's that four unrelated groups reached the same answer, and it all comes down to a date, not a weight. We look at the egg arithmetic behind age truncation, the 2018 Science analysis of fish reproduction, and why one old female is worth far more than eight small ones. Then the chemistry: methylmercury in muscle, PFAS in freshwater fish, and why trimming fat only helps with some contaminants. We cover the Munduruku mercury studies in the Amazon, the Amazonian folk category of peixe reimoso, geosmin and MIB off-flavour, farm harvest sizes of about a pound and a half, the 2023 Po Delta wels catfish, and the 88 percent freshwater megafauna decline between 1970 and 2012. Next time you stand at a fish counter or look out at your local river, you'll know what the size of a fish is really telling you. This video is educational and is not medical or professional advice. Topics covered: The fish size ceiling Why big females matter most Mercury in river mud PFAS and forever chemicals How old giant catfish really are Folk taboos as early epidemiology Geosmin and the muddy flavour Why processors reject giants Endangered giants and invasive catfish #CatfishFacts #FoodScience #DocumentaryExplainer