Lefty Kreh, one of the pre-eminent sport fishermen of his time, died on Wednesday at his home in Cockeysville, Md., north of Baltimore. He was 93.

His granddaughter Sammantha Aus said the cause was congestive heart failure.

For a half century, Mr. Kreh, a globe-trotting fisherman, journalist and author, was a colorful and highly influential figure in both freshwater and saltwater fly-fishing. In countless articles and more than 30 books, in videos, on television and at innumerable public appearances, he converted his vast experience into lucid observations and practical advice for anglers at all levels.

Mr. Kreh was always willing to re-examine traditional ideas in a sport laden with them. As he said about fly-fishing for trout in his book “Advanced Fly Fishing Techniques” (1994): “I feel that many people who are not really versed in the sport have either written or spoken about it, and they have attempted to create a concept that this is a very difficult sport to master. That simply isn’t true.”

While fly angling in fresh water for fish like trout and salmon is an old sport, saltwater fly-fishing is comparatively new, and Mr. Kreh was one of its earliest champions. His book “Fly Fishing in Salt Water,” which he said he wrote “not to make money, but so I didn’t have to answer so many darn questions,” was published in 1974 and remains an essential text.