1.   A few saltwater species, like sailfish, have long been reproduced synthetically because their oily skin deteriorates quickly.

2.   A few saltwater species have long been reproduced synthetically because their oily skin deteriorates quickly.

3.   But there have been recent experimental successes with a variety of saltwater species, like halibut, mahi-mahi and flounder.

4.   The toughest fish are the saltwater species, Fields says.