Largemouth Bass
Paul Prentiss
When & Where:

As spring overtakes Colorado, fly fishermen along the Front Range start thinking about bass fishing our lakes and farm ponds. Largemouth Bass become active and very aggressive during the spring spawning period which generally coincides with runoff. For many years I waited for the rivers to clear so I could start trout fishing. What a huge mistake. I missed out on some of the best bass fishing of the year.

Largemouth Bass were first introduced in Colorado in 1878. The largemouth bass is the largest and most popular member of the Centrarchidae family of sunfish and its subgroup known as black bass. Like all sunfish, largemouth are nest builders, spawning in 18-36 inches of water in late spring when water temperatures reach 65° F. Males guard the nest and young for two weeks after the eggs hatch. The diet of bass changes from zooplankton to other food including fish, frogs, and crayfish when the young reach a length of two inches.

Their coloring is mostly green, ranging from olive to dark green on the back and greenish yellow on the sides, with a white or cream-colored belly. A series of dark splotches form a horizontal stripe that extends down the length of the sides along the lateral line. In some circumstances, especially very muddy water, the largemouth may lose much of its coloring, appearing almost white or very light green.

The largest largemouth bass ever caught weighed 22 pounds, 4 ounces in Georgia in 1932. The Colorado record came out of Echo Canyon Reservoir (Archuleta County) in 1997 and weighed in at 11 lbs 6 oz. I have heard about larger fish being caught and I personally witnessed a fish released at a private pond in Boulder that had to be well over over 10 lbs.

As the spawn approaches in early spring, Largemouth transition from their winter holding patterns in deep water toward shallow spawning sites. Because farm ponds and other small bodies of water warm rapidly in the spring, bass fishing starts earlier there than it does on large lakes and reservoirs. They remain in the shallow water throughout the spawn, though sometimes retreat to deep water near the nests during and shortly after spring cold fronts. Once the spawn is complete, many Largemouth will remain in shallow areas until water temperatures rise above 72 F. Then they often establish summer residence in deeper water, moving shallow to feed early and late in the day, or at night.

Almost all the public ponds and small lakes in and around boulder have Largemouth Bass in them. You could start with the Sawhill Ponds Wildlife Preserve (18 ponds) that is owned by the Colorado Division of Wildlife and managed by the Boulder Open Space and Mountain Parks Department. It is located east of the Boulder city limits on the west side of 75th Street, 0.6 mile north of Valmont Road. Stop by a fly shop and ask for specifics on other options along the Front Range.

Cover is Key:

The Largemouth is a predator that prefers to hide in or behind some type of cover so it can ambush its prey. Its body shape allows it to swim easily among weeds and other forms of cover and it is designed for short bursts of speed rather than fast swimming for long distances. Though it will occasionally chase potential food for a short distance, it would rather stick close to cover and strike quickly from ambush, wasting as little energy as possible while collecting its food. In waters that lack sufficient cover, they will be found in deep water near drop-offs, channels and rocky bluffs. Largemouth bass are not migratory by nature, preferring to stay in holding positions within a given area for extended periods of time.

That means it is important to be able to recognize the types of cover (weeds, tree stumps, logs, rocks, brush piles and other submerged structures) that attract bass, and be able to accurately present your fly where it will attract the bass attention. In general I find that fishing deliberately, thoroughly and very slowly will provoke more strikes than making a lot of quick casts and fast retrieves.

Wading or casting from a float tube, canoe or boat allows the angler to cast towards the bank, which allows him or her to fish the deep-water side of cover that is more likely to attract fish in the spring. When a fish is hooked, the angler is in good position to guide it away from weeds, branches and other obstructions. The deep water position also allows the angler to cast to fish-holding spots that are difficult to see or recognize from the bank.


The choice of tackle is largely determined by the conditions encountered and techniques pursued. For this discussion I'll focus on what I find works best. I like a 9-foot 8-weight fast action rod coupled with a weight-forward line. This may seem like a very heavy outfit to some readers but it can toss out large deer hair bugs and heavily weighted streamers. New high performance 8-weight graphite rods from various manufacturers are light and strong. A secondary benefit is that such an outfit is perfect for pike and some saltwater fishing.

A nice reasonably priced single action reel that balances to the rod is all that is needed. We're not talking about a fish will take you into the backing.

While most Largemouth Bass are taken on or just under the surface you will need more that a weight-forward floating line. There are times that a sink tip or a full sinking line is required to get down 10 feet or more. Several years ago I began using multi-tip lines with a series of interchangeable tips - floating through fast sinking. They are a bit pricy but a lot less expensive than buying individual lines and reel spools.

Leaders are determined by the conditions you are fishing in, type of line you are using, the size of the flies and so on. In general shorter is better. I'll use tapered and non-tapered leaders under 8 feet and will have a 3X or better tippet. Keep in mind, these fish will head straight into heavy cover when hooked and you'll need to put significant pressure on them.


The bulk of the largemouth bass diet consists of other fish such as bluegill, shad, shiners and other minnow species, small catfish, and other sunfish, as well as large invertebrates, crayfish and frogs. In addition to their core diet, they are aggressive and opportunistic predators that may eat whatever creature they can ambush, including ducks, snakes and small turtles. The main limiting factor in prey for largemouth bass is size because they swallow food whole.

As such the range of flies covers just about everything under the sun. Large deer hair bugs, cork, foam or plastic poppers that make noise and imitate frogs and other creatures are very popular. Some patterns swim only on the surface while others are designed to dive and return to the surface depending on the retrieve. Rabbit-fur flies, Clouser style minnow imitations, Dragon flies, and more are on the list of must-have bass flies. Stop by a fly shop and ask to take a look at their selection and you'll be amazed at the range of possibilities.

To get started my advice is to keep it simple. Ask the fly shop operator to pick out a half dozen top water or floating bugs and a half dozen minnow patterns.


If you cast something to a bass that looks and acts like food chances are he'll eat it. The reason is simple. The bass is a predator of opportunity who will strike when his instincts are triggered. If you are swimming a frog imitation across a pond it has to act in a realistic manner. That means that it swims several strokes and then pauses.

You'll catch more fish if you do not shy away from thick cover. Putting a large weedless fly into such places can elicit a savage strike.

Largemouth will often watch prey on the surface for a long time before striking. There was an old but true rule. Cast your bass bug to a likely looking spot and light a cigarette and relax for a few minutes before giving it a slight little twitch. I've done this (without the cigarette) and right after the slight twitch the bug is virtually sucked down in a swirl - an experience you'll not soon forget.

While Largemouth rarely travel in schools, several fish will gather near an attractive spot, and similar spots will also hold fish in the same body of water.

Although many fly fishermen concentrate their efforts on surface feeding bass (I'll admit it's the most fun) great sport can be had below the surface where streamers, baitfish imitations, nymphs, and the like are effective. Try continual or stop and go retrieves at various speeds until you get results.

Fishing deep takes even more patience and attention than fishing on top. The reason is how bass take the imitation. They will come up behind the prey dipping downwards and inhale it without turning away. As such the take can be difficult to detect. The best way to deal with this situation is to keep constant tension on the line.

Don't be afraid to try various colors and sizes. I had a great day bass fish several years ago swimming a two inch mustard yellow mouse a few inches from a rocky shoreline. I've tried this same pattern and approach subsequently with limited success. The point is you just never know until you give it a try.