Getting fish to breed in captivity is hard. When the fish are half-ton cruise missles, it's even harder.
But bluefin tuna are so valuable that it's worth trying. Now a self-proclaimed fish whisperer says he's done it.
"We get into their minds, we find the Y factor," said Hagen Stehr. It involves massive tanks, mood lighting that simulates moon and sun cycles, and the right temperature.
Is it worth all this effort? Probably, since bluefin tuna are endangered, and worth a fortune when they're ready to sell to Japanese fish markets, upwards of $50,000 each for the best fish.
"Some fish are easier than others to breed," he said. "The southern bluefin tuna is the holy grail, the cream of the cream, the ultimate."
And if you think fish sex isn't interesting, here's a marine biologist who says the sex lives of fish may unlock some of the mysteries of human sexuality. See, fish ARE sexy.