Color vision is used by fishes to help them see prey against a variety of backgrounds.
Duplicating the exact color of a prey item is less important than choosing a color that ensures
good contrast between your fly and the background. For example, chartreuse is a color that does
not occur in nature, yet can be an effective color choice for a fly because it is so visible. Not only
is chartreuse well within the visual range of a fishes eye, it is also fluorescent when exposed to
ultraviolet light, and many fish can see into the ultraviolet range. Red and white is another
effective color combination, but many fish (including reds and trout) cannot see red; instead, red
appears as a shade of gray. Red and white is effective because it has good contrast against a
variety of backgrounds. Gray and white would be just as effective.
The amount of light available and the color of the background is dependent upon a number of
factors, including time of day, water clarity, bottom type, water depth, and vegetation. A fly with
high contrast would be more visible under low light (sunrise/sunset) or turbid water conditions.
Black is a good color choice at night because it provides the best silhouette against a moonlit sky.
Fluorescent colors are highly visible on cloudy days, when ultraviolet light is more prevalent than
clear days. A fly with high contrast is less important in clear water and on bright sunny days, and
may even “spook” some fish.
Finally, in addition to vision, fish also depend on hearing and smell to help them find prey. A
large fly that “pushes” a lot of water can be detected, even if they can’t see it. Poppers and
gurglers are examples of flies designed to make noise. Also, some fly anglers targeting black
drum have used “spray-on” fish attractants with great success.
In summary:
• Fish can see color, but they use color vision to help them find prey against different
backgrounds, not necessarily to identify prey. Fish cannot see color at night.
• A fish’s eye is adapted to see movement and contrast at the expense of detail. An exact
replica of a prey item is not necessary, but movement and general shape is.• Many predatory fish are well adapted to find prey at sunrise and sunset.
• In general, the brighter the day and the clearer the water, the lighter your fly should be.
Consider the background when choosing a fly.