The migrants. They came in early spring when the air still had a bite and the river flowed swift and full from melting snows and ceaseless rains. There were white perch, then herring, American shad and, finally, the aristocrat of them all, the stiped bass. Small and large, skinny and fat, the silver bodies cloffed the river, drawing hordes of anglers to the Potomac.

But the runs have abated now. The hering and perch have gone down to the sea, and while there are a few stripers to be caught, the shad that remain are spent from spawning, ghostly shadows of the vigorous swift fish that surged in brazenly from the ocean in March.

Is fishing in the river dead, then, with the departure of most of these tourists and, with them, the shoulder-to-shoulder crowds of spring fishermen?

Jack DeForest, retired environmental economist with the Commerce Department, doesn't think so.

It had been some time since he'd last been fishing, but recent tales of fish in the Potomac stirred him to drag the dusty tackle out of the closet the other day.*tA small tidal feeder creek close by his home near Mount Vernon gave DeForest an idea. He dug a few garden worms, drove to the water and draped a wriggling bait on his hook. Tossing it in the creek where the water swirled dark and enticing beneath an undercut bank, he waited.*tThe faintest of tappings soon telegraphed through the rod tip. He pulled back with a twitch. Ten precarious minutes later an 11-pount channel catfish, sleek and shiny, with rich gray flanks, was hoisted from the creek.

Calming trembling fingers, DeForest baited up again, flipped out the wormdraped hook and proceeded to snatch up a 4 1/2-pounder. He quit and drove home, elated with the results.

A few days later, he took a neighbor boy out - in a sailboat, of all things - behind his house on Doe Creek, another tidal feeder just below Washington. Baiting up with worms again, the pair flicked their rigs toward a dense bed of lily pads near shore. In minutes, the bobbers sank and a pair of three-pound channels came trashing to the makeshift fishing boat. Three hours later, when they quit from fatigue, the pair had landed 19 channel cats ranging from two to four pounds apiece - a 45-pound stringer.

So much for Potomac fishing being "dead" once the silvery migrants of spring vanish. The old channel cat is a tough customer on light tackle and, skinned and filleted, fries up to a mouth-watering golden-brown delight.

Almost all of the feeder creeks along the river below Washington have good pupulations of these whiskered graycoats. But you don't have to go south of the city to find them. There are plentiful supplies of catfish right in town.

Shore fishing on the bottom with time-proven baits such as Ivory soap, chicken liver, nighcrawlers, minnows or cut pieces of fish is a sure way to snare a mess of these tasty fish. Concentrate on coves, points, the edges of island and mouths of feeder creeks. Action should be consistent through summer and early fall. Rental boats at Fletcher's lend access to additional catfish water unreachable from shore.

But cats aren't the only full-time residents of Washington's stretch of the Potomac. Bass-casters are finding good numbers of largemouths in the waters from Chain Bridge south around such well-known landmarks as Roosevelt Island, National Airport, Kennedy Center and Hains Point.

Pete Cissel, who guides bass parties for a living on this part of the river, has found interest so keen that he's now offering half-day trips - 6 to 12:30 and 1 to 7. It's a tempting way to top off half a day's work with half a day's pleasure.

While fishing often slows on big bass lakes during summer months, Cissel says action on tidal rivers such as the Potomac "just gets better." Already this year has seen one 6 3/4-pounder, several five-pound bass and many four-pounders come to his clients.

Phone 577-8274 for more information.

For those who want to try the river on their own, Cissel recommends small Fliptail lizards fished on 8- or 10-pounds line with an eight-ounce slip sinker. Black firetail worms are also good. For deeper spots, chartreuse crankbaits get the nod.

Bridges will produce off and on, especially on a moving tide, but Cissel recommends fishing the pilings farther out toward midstream as summer progresses. Roosevelt Island, the stone wall at Watergate, Hains Point and Washington Channel are other good hot-weather fishing spots.

Other places Cissel likes during summer are the big bell channel markers on the outside bends of the river. "There are usually pilings there, where the deepest part of the river channel was when big ships used to come in. Catch these on an outgoing tide and they can sometimes be real good."

Boats can be launched just north of National Airport on George Washington Parkway or at Fort Washington Marina in Maryland, off Indian Head Highway.

If bass and catfish don't strike your fancy, bluegills, crappie and a handful of summering stripers are also in the river around Washington. You won't find hordes of shaddarters, perch-snatchers, and herring-snaggers vying for every unpeople rock along the river in June or July. What you will find is an abundance of resident gamefish ready and william to do battle for the rest of the summer. And you'll waste neither gas nor time driving for hours on end to distant angling spots that may not prove as good as our own Potomac.

There are plenty of fish in our own backyards. CAPTION: Picture, A FAT CHANNEL CAT FROM THE POTOMAC. By Gerald Almy.