In 1995, Adrian Piers, a veteran aquaculture consultant, imported a batch of Australian red claw crayfish to the tiny southern African monarchy of Swaziland. He began raising the attractive blue-green crustaceans — the males of which have red stripes on their claws and can weigh a little more than a pound — in ponds rented from a sugar estate, and soon found a market for them among French-style chefs in neighboring South Africa.