Walleyes are known for their marble-like eyes, which let them see well in dim light. Their retina has a layer of reflective pigment, called the tapetum lucidum, that intensifies any light the eye receives. (It's the same membrane that causes a cat's eyes to glow yellow.) But the walleye's close relative, the sauger, has even better night vision because the tapetum covers a much larger portion of its retinas.

Ever wonder where the term "black bass" came from? The fry of smallmouth bass turn coal black within a few days after they hatch. Even though the fry of largemouth and other bass species do not turn black, all members of the group (genus Micropterus) are referred to as black bass.

Researchers studying walleye vision found that orange is the color most visible to walleyes, followed by yellow and yellow green. Surprisingly, red is the least visible color. No wonder you find so many orange and chartreuse lures in the tackle boxes of savvy walleye anglers.

White and striped bass are members of the temperate bass family, as opposed to black bass, which belong to the sunfish family. The term "temperate bass" refers to the moderate water temperature preference of members of this family. As a rule, they prefer temperatures a little lower than those preferred by largemouth or smallmouth bass.

Trout are the only kind of fish with an adipose fin, right? Wrong. Several other fish species, including catfish, bullheads, madtoms, smelt, ciscoes and whitefish, also have an adipose fin (the small fin on the back just in front of the tail).

Flathead catfish have a tooth pad consisting of hundreds of tiny, recurved teeth on the roof of their mouth. The pad helps them hold their prey securely, so it can't wiggle around and escape. So if you're inclined to stick your hand into a flathead's mouth to dislodge your hook, forget it. You might pull your hand out minus the skin.

Flatheads are often called mud cats, giving anglers the impression that they scavenge dead food items off the bottom. But flatheads are more apt to eat live fish than any other catfish species. Channel cats are most likely to consume dead, stinky food (and bait) and blue cats are intermediate in their food preference.

Members of the sturgeon family are the largest fish inhabiting the fresh waters of North America-and some are also among the smallest. The white sturgeon, which is found in rivers along the Pacific Coast, has been known to reach a weight of almost a ton, and today's anglers of the Pacific Northwest commonly catch whites in the 200- to 300-pound range. Shovelnoses, on the other hand, seldom exceed a few pounds in weight in their Midwestern home waters.

The very best time to catch a trophy walleye is five to seven weeks after the fish have completed spawning. That's when the big females, famished after not having eaten for nearly two months, go on the prowl for food. And with the natural supply of baitfish at its annual low, they're likely to hit almost anything you throw at them.

An international team of scientists has confirmed that the dorado catfish (Brachyplatystoma rousseauxii) of the Amazon River basin holds the record for the world's longest exclusively freshwater fish migration, an epic life-cycle journey stretching nearly the entire width of the South America continent.