Why you should fish nymphs more than dry flies!
The answer is very simple. You will catch more fish.
Several studies have shown that 80 to 95% of a trout’s diet is sub-surface.
A trout is a predator. Predators hunt. Trout must get more energy from the food they consume than the energy it takes to obtain the food. Or they will die. It is a simple equation. Energy in must be > Energy out or Death occurs.
So which is easier to catch. Hundreds or thousands of sub-surface insects or something flying around mating and dipping down to deposit eggs. Pretty simple — nymphs are easier.
Basic Stream Entomology — the short course
A trout’s 6 basic food groups (This is primarily in Colorado but applies to much of the surrounding states too)
Consists of clingers and swimmers
First hatch of season (BWOs can be in March to May and last of season in Sep and early Oct) Exist in hundreds of thousands in some areas of steams. Fly pattern olive body with white antron yarn wing RS2 sizes 18 through 22.
Other mayflies during warmer months of May through July
- Stone Flies
Clingers or crawlers mostly — You can find them by turning over rocks. Colorado doesn’t have the salmon fly hatches of Montana but where there are hatches of large stoneflies, you can see some hot action.
Hatch usually by crawling out onto stream bank for large types like salmon flies. Once on the South Platte River below Waterton Canyon, I saw a hatch of large stone flies. The beach was alive with them crawling out of the water. One I let sit on my hand had a body about 4" long.
Yellow Sallies and small black stones are also a choice food group. I like the gold ribbed beadhead prince nymph in sizes 12 through 18 as a general pattern for black stones. Fish straight upstream or quartering upstream, drifting down and then swing in toward the downstream bank before pickup.
Cased, crawlers and net builders are the main types. Caddis are perhaps the most important food group for trout next to the midges. There are over 2,200 different species of caddis.
Cased may be attached to twigs or small rocks and have a wood casing. Some caddis form cases of small rocks with their saliva and attach themselves to rocks until time to hatch.
Crawlers — are free type worms that look like a meal worm or grub. Generally represented by the buckskin nymph in sizes 16 and 18. These can be found by turning over rocks or sticks.
Net Builders — can be found in shallow riffles of areated water where they build silken webs to catch their food brought by the current. Sometimes they can also be found with a web between twigs on a sunken branch.
Caddis can be represented by gold ribbed flashback bead head hare’s ear. or the plain head gold ribbed hare’s ear sizes 14, 16, 18. Elk hair caddis for the mature adult if you are fishing dry flies. Fish the nymph dead drift the use the Leisenring lift at the end of the drift to simulate the rapid rise to the surface of the emerging caddis. During a Hatch fish a Caddis dry trailed by an emerger.
All caddis in Colorado have 6 legs total. 3 on each side of their head. A black head. Body may be tan, whitish or green.
Are the year round food group in Colorado Fly Fishing. There are millions of these insects in the streams. They are small with sizes often running 20 to 24. But the trout easily pick them out and eagerly consume them. Gray, olive or tan RS2 can be used to imitate them.
Ants, beetles, grasshoppers or other terrestrials that fall into the stream may be eagerly sought out by trout. Trout seem to favor the acid taste of ants in particular. (Large ones of course)
- Other sub-surface food groups such as crawfish, sculpins, minnows, eggs during mating season of other trout species, other young of their own and other trout species.
A nuclear egg pattern representing a fish egg surrounded by milt can be deadly fished on the bottom. Bill Louthan of Alpine Angler in Aurora, CO caught an 8 lb rainbow on an egg pattern in Troublesome Creek last year (2004)
Sculpin and streamers would represent small fish that trout prey on.
Set your rod up for a 2 nymph rig
Shown is the business end of a two fly nymph rig using a #16 bead head flash-back gold ribbed hare’s ear for the top fly and a #18 gray thread body silver ribbed RS2 on a 7X dropper.
I like to use 3 Dinsmore egg shaped split shot about 6 inches below the top fly and 2 Dinsmore Split shot the next size up about 6 inches above the top fly.
Below is a set up for about a 12ft 6 inch nymph leader. Janice O’Shea professional guide teaches her students to use a 7.5 foot tapered leader to 4X as a base. Then 1 foot of 5X and 18 inches of 6 or 7X if needed as a tippet.
I like her setup because it means less leader to deal with and less time to set the hook than longer leaders.
To Strike Indicator or Not
When I was learning to nymph fish, there were no strike indicators. We made a little J slack in the fly line at the water line and watched the J for any suspicious movements as a clue to set the hook.
Today there are yarn, round micro balls, oval shaped foam with rubber band inserts, foam with adhesive backing and more. Frog hair has just come out with a new indicator that looks promising.
The foam with adhesive backing should not be used because they come loose from your leader and float down stream. Trout mistake them for food and eat them. The trout cannot digest the foam and they can die as a result.
I personally like one white yarn indicator. But yarn eventually becomes water logged no matter how much floatant you use. A yarn indicator also is hard to cast into a strong headwind and to adjust up or down the leader.
The round micro balls that use a rubber band as a friction holder against the leader are good. They are easy to adjust up or down the leader which is a real plus as you try to find the depth the trout are feeding at. These are usually a day glo orange color and easy to see on the water.
The oval shaped foam with a rubber band insert is not too bad. But one end or the other can become separated and break off the leader floating downstream. Then you have the same problem as with the adhesive backed foam indicators. (Trout mistake them for food)
Frog Hair’s new EZ-On indicators come in sizes micro through extra large. They thread through the middle of the indictor. The EZ- On is designed for a single use application and contains a built in friction retainer. Each package contains 3 orange and 3 yellow and orange indicators. The shape is oval and should float true with the leader through the center of the indicator.
Frog Hair’s new Ultimate indicator is shaped like the EZ-On but is is designed for multi-use. The retainers are separate. Each package contains one hi-viz orange and 2 two tone indicators.
The newest thing is the Thingamabobber. This is a soft vinyl indicator much like the foam balls but with a metal tab used to attach the leader. The Thingamabobber was developed from guides blowing up small party ballons and attaching them to the leaders to be used as strike indicators.
Whether you are using micro balls or Frog Hair’s indicators, use one smaller one on top and a larger one about 6 inches away from the small indicator. Keep sliding them up and down the leader until you start catching fish. This is the level you should use until conditions change or you move to a different part of the stream.
My tests of strike indicators this last year were positive. I am sure that I caught fish and larger fish with indicators than without. It is good to practice the J method too. There will be times when the water is too clear or low to use an indicator effectively.
A strike indicator is not advised for the Czech Nymphing method. Generally you will be fishing in fast water with this method using a short tight line and the indicator will not be needed.