Posts were appearing on my Facebook feed warning against the dangers of eating tilapia. So I decided to do a little research. My dad was a seafood wholesaler at the Fulton Fish market, and as a kid I’d encountered all manner of fish, at the dinner table and from working one summer at his stall. I knew about porgies, red snapper, flounder, and crabs galore, and that gefilte fish was a mixture of carp, whitefish, and pike. My dad even dealt in turtles and he’d send the occasional mystery species uptown to the American Museum of Natural History for identification.