UK Fly Fishing Expert Martin Cottis

As resident Guide and Instructor at Chew and Blagdon, Martin Cottis is perfectly placed to give us the benefit of his reservoir fly fishing experience.

Not so many years ago there were only a few reservoirs open to trout anglers, and the use of boats was strictly limited to certain privileged anglers. Now, there are many public water supply reservoirs, where, due to legislation, all sorts of amenities are catered for. Thankfully, clean water to be supplied for public consumption is usually of good enough quality to sustain trout, and as a result, there has been a boom in trout-fishing on reservoirs.

My introduction to the big English reservoirs happened on Bewl Bridge Reservoir (as it was known in my student days) and, having only lightweight gear that was more appropriate on rivers or small stillwaters, I felt somewhat inferior. Especially when tackling up next to the regulars armed with 10-11ft rods and flies the like of which I’d never seen before. Back then, the pioneers of reservoir boat fishing cast aside the delicate approach favoured by river anglers. Instead, 8 weight rods were standard, and sinking lines generally ruled the waves. Thankfully, as fishermen became enlightened over time, more delicate outfits replaced these. My teaching career took me to Bristol and the opportunity to fish with Chris Ogborne, who in those days led the way when it came to the light-line approach. I had developed most of my trout fishing skills along the lines of Brian Clarke’s approach in his book “The Pursuit of Stillwater Trout”. Such influences saw my lures and sinking lines become redundant as I wholeheartedly adopted the Bristol style of fishing.

Western2 Rods

Fly Fishing for trout in a UK ReservoirThese days, working as a professional fishing Guide and Instructor at the Bristol Water Fisheries (Chew and Blagdon), my technique has evolved to be almost entirely based upon an imitative approach and the heaviest line I carry is a 6-weight. Over several recent seasons, the Orvis Trident TL rods have served me well. However, in the last year, I have been in the privileged position of fishing with prototypes of the new Orvis Western2 rods. A session with the 10' 5-weight, 3 piece Western2 rod proved interesting, to say the least. Quick, responsive and well balanced, this new rod performed beyond my expectations. Even when faced with gusty conditions, I wasn’t left wanting. Light and sensitive, the 9'6" 6-weight, 3 piece model was equally impressive and I’m certain it will become a favourite of mine. This rod was so powerful—I am amazed at how modern manufacturers can get so much power into such light materials. A long-time fan of the trusty Orvis Trident rods that are sadly no longer made, the Western2 series will more than fill a gap in my armoury.


Supple and fine in diameter, Superstrong tippet is my only choice for dry fly work and occasionally nymphing. With the wind on your back, turnover is rarely an issue so a straight leader of 3X (8.5lb.) tippet works just fine. Whilst this may sound heavy, the fish don’t seem to mind so long as the leader is thoroughly degreased – and just below the surface. A floating leader is the biggest cause of fish shying away from taking a dry fly or an emerger. Naturally, given bright, calm conditions, 4X (6lb.) tippet might be considered. However, when nymphing proper there’s no substitute for Mirage fluorocarbon tippet, and again I tend to look to the 3X (9.2lb.) and 4X (7lb.) sizes. I tend to use a two or three fly team on the big reservoirs, though I am happy to go down to a single fly if the fish are being more selective. With only one fly on, it is essential to use an Orvis knotless tapered leader.

Martin Cottis Fly FishingDry Flies and Nymphs

The dry flies I use are simplicity itself. A seal’s fur body and small amount of hackle is all that is required. The flies should be tied in various shades, but just match them with whatever midge are hatching from your local reservoir. Standard colours will be red, claret, black and maybe orange. My favourite size would be a #14, but I generally use a #12 on the point with two #14 flies up the cast.

On most working days I try to find rising trout for my clients, for to take trout on dries or emergers on a big reservoir is quite a challenge. Many of my clients are river fishers and they struggle to work out where to cast at a rising fish. Unlike in a river, where that trout is almost certain to be facing up-stream and often visible, on a reservoir, the fish may be moving in any direction and unless your eyesight is keen enough to get a decent view of the rise, you are likely to cast in the wrong direction. The speed at which the fish is moving needs to be assessed so that you will work out where you will cast your fly. Unless you can calculate these two aspects carefully and quickly, you will rarely meet with success. There’s nothing more satisfying than seeing newcomers to reservoir fishing encounter fish that may have otherwise gone unnoticed without my services.

In the absence of moving fish and when searching dries fail, nymphs are the order of the day. This requires a slightly different approach and the first thing to consider is the boat’s drift. A drogue ensures a slow, steady drift, allowing the nymphs to be presented more naturally. Leaders also need addressing and can frequently attain some twenty feet in length. As to flies, along with imitative buzzers, suggestive patterns like Diawl Bachs, PTNs (Pheasant Tail nymphs) and Hare’s Ear nymphs are what I reach for.

Other Gear

Everything is loaded into my Super Tac-L-Pak vest with tippets, flies, floatant, etc. so that they are instantly to hand. Spare reels, waterproofs and other bits can be stowed in the Safe Passage kit bag which has transparent pockets to help locate items quickly.

UK Fly Fishing Expert Martin Cottis
Martin Cottis