Quote Originally Posted by colayn View Post
Anyone know why some black crappie have black vertical bar on the eyes?
On some lakes its almost all the blacks, other lakes its a mix of both regular eye no bar and with bars
Here’s what is received from KDFWR

The dark vertical bar through the eye is a general characteristic of both species of crappie, but the intensity of the dark pigment can vary depending on water clarity and perhaps other factors as well (e.g., water chemistry, temperature, light, etc.), as Eric suggested. I have noticed that fish taken in clear or darkly stained water are more boldly marked with dark pigment (vertical bars and mottling), whereas ones taken from turbid or muddy water are more pale or washed out.

Overall color and pigment patterns are determined by the animal's environment and behavior. The dark vertical eye bar of the crappies may be used for visual signaling between individuals (e.g., for schooling) and it may serve as camouflage by presenting a disruptive pattern along with the irregular vertical bars and mottling on the body and fins.

Other members of the sunfish family such as the Flier and Rock Bass also have a dark vertical bar through the eye. An old published study by Barlow (1972) showed that vertical eye-lines (bars) are often associated with fish having deep bodies and steep foreheads that swim up in the water column and turn sharply (e.g., crappies and other sunfish), whereas horizontal lines are characteristic of more long, slender bodied fish with low foreheads that are often bottom-dwellers (e.g., sculpins).