Discovering Daphnia

They are of primary importance to lake and pond fly fishers; however, I’ve also occasionally seen river fish feeding heavily on daphnia below lakes or reservoirs that have daphnia blooms.

Daphnia Fly Patterns

The size of many other flies may be critical, but not with the Tullis Daphnia Cluster. You’re imitating a cluster of varying size, not an individual of specific size. I’ll go from a standard #16 hook in streams to a 6X-long #2 hook in some big trout lakes, and they both work. I use a 3X-long #6 or #8 streamer hook most often because the hook gap does less damage to trout than a #2, but it is still large enough to interest trout. Smaller offerings, #16 to #12, are better for stream fishing or in clear-water conditions.

I have used many colors of mohair yarn on the body but am convinced that mixed fiber colors best imitate the natural iridescence and color variation of many naturals. Canadian brown, Canadian blood, pond olive, and lake olive are colors that have worked best for me. If these colors of mohair yarn are not available in your local fly shop, contact the source, Mike’s Fly Desk (801-292-4736). A small amount of pearlescent flash usually enhances the fly’s performance, so I add two to three strands of flash to the tail or sometimes use crystal chenille or flashy dubbing as an underbody. Just palmer the mohair yarn over the underbody, leaving some flash showing through.

Brush or pick out the mohair fibers before you add the T-shirt paint. Hold the fibers with one hand and dab the paint with the other until you have 1- to 2-mm drops all over the leech, like ornaments on a Christmas tree. Use light green, red, or orange fluorescent-colored paint. Use blue or purple to have colors last in the depths. I’ve also occasionally used black paint for the best silhouette in low-light situations.

I like to add a brightly dubbed head for less-than-clear water. Try a bright yellow, orange, or red head dubbed with a flashy synthetic dubbing. Brightly colored chenille wrapped one or two turns or metal or glass beads also make good heads and provide contrast that a trout can spot in algae-laden water. I like to lightly weight the fly under the body or use a metal-bead head.

Other patterns that interest daphnia-feeding trout include Marabou Muddlers (orange, red, or chartreuse wings), Kaufmann’s Mini-Leeches, Zonkers, brightly colored streamers, nymphs with brightly colored heads or thoraxes, colorful scuds, immature damselfly nymphs, lake midge larvae patterns, leeches, and peacock-herl patterns.

Daphnia Fly Presentations

An anchored boat or float craft best allows you to fish the various depths in which daphnia swim. Fishing from shore is possible when wading in the downwind end of a lake where daphnia collect or where prevailing winds concentrate windblown water along a shoreline and off a point that has a drift line visible. Fish transition areas, such as where the bottom slopes into deeper water or where tall weedbeds drop off into deeper water. If your fish graph shows trout are suspended over deep water, it is likely you have found some daphnia feeders, so use the line countdown method to reach their depth.

If light penetration is weak, daphnia are likely to be close to the surface. They seem to prefer clear, nutrient-rich waters, and they can be anywhere in the water column where the light reaches. Daphnia can be as deep as 60 or more feet at times but are more often in 1 to 30 feet of water.

The best lines for fishing daphnia cluster imitations are a Type I full-sinking line (uniform sink) or a SA Mastery Stillwater (clear) line. Use a Type II (uniform, full-sinking) line if you want to fish deep. Despite the slow sink rates, you can use these lines to fish down to 30 or more feet deep, if you have the patience to let the line sink to the desired depth before retrieving. Faster sinking lines usually move the fly down in the water column too quickly and move your imitation unnaturally fast. A little weight on the fly is fine, but don’t overdo it.

Patience is part of this technique. Since trout are used to seeing daphnia descend slowly, fish this fly on the sink, rather than the retrieve. You can slowly retrieve a small amount of line to keep the slack out or to move the fly into another area, but the retrieve should not be so fast as to impede the downward sink much. A 1-inch-per-second retrieve is fast enough to keep the slack out.

Frequent pauses are good, but always keep the line tight to feel light hits. Keep the rod tip low and pointed at the fly so your fingers can feel anything unusual. Daphnia feeders don’t always hit hard, but you can feel them on a tight line. Set the hook as the line tightens slightly, like a rubber band starting to stretch. At other times, the take is very distinct.

You can often fish your fly quickly right under the surface with spectacular results, especially on windy, cloudy days where the choppy, well-oxygenated water seems to attract aggressive feeders around the daphnia blooms near the surface.

A 9-foot, 4- to 7-weight rod and a short leader tapered to 2X, 3X, or 4X will do. I usually use two flies, spaced about 3 feet apart, at once. If you use two different sizes and colors, you can quickly determine which one is more productive. I go to one smaller fly only with selective feeders in clear water.

If you’re getting blown around in a boat, you can’t control the speed and depth of the retrieve. An anchored watercraft is best; a float tube or kick boat controlled with fins is second best. Keep your back into the wind and stay in place by finning and watching something fixed (a weedbed or marker buoy, for example) to gauge your own movement. If the wind blows you toward your fly, you lose contact with it; if it blows you away, you are moving the fly too fast. Tension control is paramount for ultra-slow presentations. Remember that to imitate the actual daphnia clusters, the fly must be presented on the sink, on a tight line, not with an active horizontal retrieve.

Even though the slow retrieve attracts daphnia-feeding fish, faster retrieves with the bright green, orange, or white attractor flies imitate leeches, minnows, crayfish, dragonfly nymphs, or just appeals to the fish’s curiosity.

In rivers below lakes where trout are feeding on daphnia, simply fish a small Tullis Daphnia Cluster Fly as you would a nymph. Fish it dead-drift with a strike indicator and some weight to get down to the trout’s strike zone. If trout are keying in on daphnia, a few cluster flies or small fluorescent nymphs in your box may produce well.

Two important parts of fishing are observation and experimentation. These things have opened my understanding and increased my fishing success for daphnia and the trout. When you’re stumped on trout stillwaters, experiment with daphnia flies and techniques. It just might save the day.

Larry Tullis is a frequent contributor to Fly Fisherman and author of Green River and Henry’s Fork, books in Amato’s river journal series. He lives in Salt Lake City, Utah.