The Fish was originally designed in the early '70s as a board that could be used as a kneeboard and stand-up surfboard, hence its designation as a hybrid. At the time, many surfers were infatuated with the new concept of "total involvement" surfing. Just how deep and tight a rider could surf in the curl was still being mapped out, and there were those -- influenced by George Greenough's example -- who thought that perhaps kneeriding was the best path to "total involvement in the curl."
The Fish wasn't the first split-tailed board, nor was it the first twin-fin. Both of these designs had been done in balsa as far back as Bob Simmons' and even Tom Blake's time. In fact, ultra-short twin-fins were already making the rounds in the very early '70s, before Steve Lis is credited with combining both the split tail (swallow) and the twin-fin into what came to be known as the "Fish."
The Fish was the epitome of the backyard board. The backyard revolution was sweeping through the surfing world in the late '60s and early '70s, as new ideas came faster -- and old dogma tossed away more readily -- than the big-time, cookie-cutter surf industry could react to in time. The Fish was designed in obscurity and popularized by word of mouth -- in direct contrast to the over-hyped and superstar-endorsed log models put out by the major manufacturers at that time.
A Fish board, as ridden by Reno Abellira, was the seminal board that begat the Mark Richards twin-fin era in the late '70s, and the original Fish design is still popular today. At around five-and-a-half feet in length and at least 21 inches wide, the outline appears anything but racy, but that's exactly what the fish offers. It's a potent design; even period boards that are shackled with some of the cruder features that were standard in the '70s can be much faster than a modern "high-performance" shortboard. Perhaps that is why so many young hotties scrounge garage sales and used board racks to find a vintage Fish that will give them a taste of blinding horizontal speed that the modern shortboard lacks.
Of course, the array of spin-offs that cropped up in the mid-90s and continue today -- each with its own model name, dimensions and fin arrangements -- can't rightly be called Fish. Such postmodern are generally just slightly wider shortboards with swallowtails. (The younger generation of surfers using them generally ride widths of 17.5 inches to 18.5 inches; so any board over 19 inches would be the equivalent of the '70s or early '80s surfer riding a 21-inch wide board.)
First sparked by Tom Curren's 1992 J-Bay speed run on one of Derek Hynd's custom, keel-fin Skip Fryes, high-performance fans tended to 'split the difference' between their standard dimensions and fin set-ups and the original Fish concept -- adding an inch or so of width and maybe a tiny-trailer between two normal fins. Other additions came over the next 10 to 15 years -- including a shift in popularity from twins to quads, and more pulled in tails for turns.
No matter the interpretation, such fuller, more balanced outlines and flatter rockers offered much more speed and easy lift in junk surf and showed where hotdog surfboard design was heading, best represented by the late 2000's arrival of boards like of Lost's "Rocket" or Dane Reynolds' "Dumpster Diver." (Proof that even a truly sensible or functional trend in surfboard design must be camouflaged with a gimmicky names or a superstar rider to appeal to a certain market.)
In the end, all forms of Fish are really just hipper versions of the funboard philosophy, adding some foam to make surfing more enjoyable. And though all may borrow more from the mid-'80s tri-fin than it does from the more extreme Lis Fish, they remain a welcome alternative to the super-narrow, rockered-out designs of previous decades.