What Makes A Fly Appealing to A Fish?

This article appeared in Backcasts, the bimonthly newsletter of the Northeast Council of the Federation of Fly Fishers (www.fffnec.org):

What makes a fly appealing to a fish? What features of a fly trigger the predatory instinct in a fish? What makes a fish decide to eat something that comes across its field of vision? For purposes of this article I will mainly focus on the sense of sight. There has been a great deal written about this, but let's take a look at this issue again.

Fish are first, and foremost, predators. They live stacked up in the hierarchical predatory dance system that is the natural world. The average fish spends most of its time either looking for prey or trying not to be detected and become prey. So, what does the piscatorial predator look for when shopping for a meal?

First, a fly should look like a prey item. After all, we eat things that look appealingly like food to us. A fish is not going to behave any differently. As a consumer, the fish wants to eat something that is familiar to its senses. Fish usually eat insects in some stage of aquatic development or other, often smaller, fish. I tip my hat to other food items, but for purposes of this discussion I will not focus specifically on these other dietary supplements such as small mammals, birds, fruit, etc., but some of what I say holds true for these items as well.

A fly should have the approximate shape, size and color of the prey. In the underwater world of shifting water currents and lighting, silhouette is part of this equation. The use of different furs, feathers and synthetics impart different outlines on the flies. Texture also comes into play here. Using materials wisely is important.

Second, a fly should behave like a prey item. This is deeply connected to the motion which we impart upon the fly. The fly should flow and wiggle in the water in ways that mimic the prey. Again, using materials wisely is important. There is not space here to go into depth about this, but in a future issue of Backcasts I will explore this in more detail.

Third, fish key in on eyes. When any animal encounters another, it is the eyes that meet for the final reality check. It should be noted that, relative to the size of a fish's body, the eyes are very large. This makes the issue of the eyes on our flies very important. Eyes are organs that interact with light. Given this, the eyes we attach to our bait fish imitation flies should also interact with light. To this end, it is good to use eyes made of a reflective or holographic material. I prefer the three-dimensional eyes that are domed in shape. Or I may add a dab of epoxy or Tuffleye over the flat-style eyes.

So, in my humble opinion, if it looks like food, acts like food and looks back at the fish like food, it must be food.