Grayling are easily distinguished from other game fish: they have an immense dorsal fin with twice the number of supporting rays, an under slung mouth with few apparent teeth, and a sharply forked tail. Taken together these features make grayling unmistakeable. The Grayling is a spring spawning species (unlike trout which spawn in late autumn and early winter) Grayling are also prepared to feed in lower water temperatures when other game fish are lethargic.

Stalking

My favourite style of fishing for Grayling is what is called "stalking", i.e. sneaking around trees and bushes with small flies. Casting from the bank is reasonable good especially in winter when the under growth has died down. However this means that you are easily spotted by the fish and as wading in winter is forbidden it is often necessary to tread carefully so as not to scare the fish. The Grayling are Catch & Release only and as they have been stalked many times this is easily done. Delicacy is the keynote to catching them, casting and presentation has to be extremely accurate, as they are shoal fish, fright one and this can spread alarm to the rest.

Tactics

I start by observing the water from a distance, looking for activity in the water. In my experience, nymphs, larvae and snails are far more common diet for grayling than winged insects, so a large part of my fishing is with subsurface patterns. I have also caught some of my largest fish on fairly small flies - sizes 14-20 -  where the bottom of the river is sand or gavel and the current isn't too strong it is often possible to spot fish and by their movements you can guess what they're feeding on, but most of the time I'll have to admit to fishing blind and rely on my experience to find the most likely holding spots.

Grayling often hold on sand and gravel bottoms, unlike trout who prefer places with vegetation and deep pools, so I often walk down stream fish spotting and cross the river over the  A48 road bridge and then begin making short casts upstream on the other bank. I start fishing close to land and never make longer casts than two or three rod lengths, if I don't have to. The majority of fish I have taken in this small river have been hooked within a radius of 10 to 20 feet. It is also very difficult to get the proper control of a long line in any rapid currents.
These upstream drifts tend to be very short, so it is necessary to make frequent casts and to move to new spots to get a better angle across the current.

The actual casting is simple, but the fishing technique is more demanding: This is a very active style of fishing, where you rarely can leave the fly drifting with the current, but have to make frequent mends and line retrieves to keep contact with the fly and leader.  It is important that the line isn't allowed to form a loop in the current that will pull the fly and leader downstream. The fly should drift with the same speed as the water and I often hold my rod tip so high that only the leader and the tip of the fly line is in contact with the water. For this reason it is important to study how the water is moving and how the current affects the fly, the leader and the fly line. Over the smooth, sandy bottoms where the grayling are, the water travels in an even, quite rapid flow, but there are often rocks and boulders below the surface that may slow down the water that the fly is moving with. To counteract the effects of this difference in speed between the surface and the subsurface water, I let the line land upstream of the fly, which then will get the time to sink and drift a few yards before the line tip has passed it and will begin to straighten the leader.

Equipment

Upstream nymph fishing as a rule requires quite long rods, 9 to 10 feet being standard, since these give the best control over the line and the leader in the current, but I enjoy using a shorter rod 7ft. The main reason for this is that it is simply more fun and as the river is narrow it makes it easier to operate in tight spots. Since the water can be shallow and any insects swim or drift up towards the surface I only use a floating line with a soft taper leader max strength of 4lb with a tippet of usually 3lb and small, weighted nymphs. I sometimes may also attach a small split shot or a section of Twist-On lead above the fly. Many anglers reduce the tippet to 2lb but I found it is better to land a fish and remove the fly rather than experience a line break, leaving the fish with a line trail. You are more likely to have your hook thrown than any thing else.

My favourite nymphs for stalking:

Suggestive patterns
Patterns that don't imitate as much as suggest the insect they resemble. The name doesn't say that much really, since all flies - including classic wet flies - could be said to be "suggestive". These flies are often tied with soft materials that add life and mobility in the water.

Allround patterns
Small, dark patterns on nymph or caddis hooks in sizes 14-22 with a body of dubbing, floss, Flexibody or tying thread and a thorax of hare's ear are efficient imitations of anything from caddis pupae to small water beetles.

The Red Tag, Green insect tied with or without a red tag, and the weighted polish nymphs are popular also some attractor patterns with some purple, red, copper or silver in their bodies, can usually be seen in my fly box.