ok heres your answer from the book "Fish" by Peter B. Moyle
Red coloration: In a world filled with predators, it seems strange at first so many fish are bright red or have red spots, stripes, or fins. "Red snapper is commonly sold in supermarkets; cardinal fishes and red squirrel fishes are among the most abundant fishes on coral reefs; the upstream migration of sockeye salmon, with their green heads and bright red bodies, is a frequently photographed spectacle. Although red is one of the most visable colors (to us) on land, it is frequnetly one of the least visible in water. Water is a selective filter of the colors of the spectrum, and red is filtered out in the first few meters. Red is also the first color to fade out at dusk and the last to appear at dawn. Thus most red fishes in the ocean live below the depths of red light penetration or are active only at night. Either way, they are difficult to see.
In shallow water, many fishes, such as sticklebacks and trout, use red as a breeding color. The fact that most such fishes confine the red to the males and develop it only during the breeding season is a good indication that it does make them more vulnerable to predators. This is balanced by the fact that bright color seems to make males more attractive to females. Red for such fishes represents a compromise between these conflicting demands of attracting females and avoiding predators because it is highly visable at close range or in bright light, but considerably less so at a distance (when viewed at an angle through water), or when the fish is under cover or in the shade... You were lucky that I was studying for class or you never would have known Rusty.

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Blaino
Arcata/Redding CA


[This message has been edited by Blaino (edited 20 January 2006).]