Catfish: What You Need to Know About How They See
July 12, 2017
During a recent fishing trip, one of the fish I managed to land turned out to be a blind blue catfish. Both the fish's eyes had been injured and destroyed somehow. Yet despite this disfigurement, this 16-pound catfish was still very healthy. Its belly was bulging with food. It fought powerfully when hooked and swam away quickly when released.
Incidents like this prove that catfish don't require eyesight to find food. When necessary, they compensate for blindness by employing their other extraordinary senses. They do so daily in some environs, even with normal eyes. In muddy water, for example, vision may be so limited, catfish rely totally on other sensory elements — taste, scent, sound, etc. — to pinpoint meals. The fish live healthy lives, nevertheless. Does this mean catfish eyes are useless? Of course not. Catfish have excellent eyesight, despite popular misconceptions. Vision aids them in ways you might never imagine. Did you know, for example, catfish fear shadows? Scientists discovered this while studying catfish senses in the laboratory.
"We found our experiments could be fouled up for weeks just because someone put their hand over the top of a tank,"
said Dr. John Caprio, who conducted the studies at Louisiana State University. Dr. Caprio's laboratory had overhead lighting. If something passed between the lights and one of the aquariums, creating a shadow, the catfish in the aquarium scurried into a plastic tube the scientist had provided for the fish's security. Only when the shadow was long gone would the catfish venture back out to feed. Why is this happening? Dr. Caprio wondered. Could it be a response to predators? To see, he placed a bird predator silhouette above a tank. "When I did that, the catfish went into its tube and would not come out," Caprio says. "It would literally starve to death before it went out to get food just inches away '¦ unless you turned the lights off and the shadow disappeared. Then it would come out immediately and feed." We can say with certainty, therefore, that the eyes of catfish help them avoid animals that might prey on them. They see a shadow pass overhead and they hide somewhere to avoid the creature that made the shadow. Remember that next time you're catfishing: shadows are bad karma. That's why night-fishing and fishing from a distance often are more productive, particularly in clear waters. Never cast a shadow on the water you're fishing if you want to enjoy success. Do catfish eyes detect more than shadows? Yes. Cones in the eyes indicate catfish have color vision, and this is borne out by the experiments of some anglers.
In his book Catfishing (North American Fishing Club, 1992), author Chris Altman, an avid cat man, wrote about one angler who places half-inch sections of plastic worms on his hooks along with his baits, primarily to provide a splash of color.
"The piece of plastic worm makes the bait a bit more buoyant," the angler told Altman. "But I believe it functions most effectively as an attractor to the catfish, something to get the fish's attention. We have done informal studies on the technique and, invariably, the angler using the piece of plastic gets a bite more often."
Catfish eyes also have structures that enhance their ability to feed at night. Rods improve their sight in dim light, and each eye is lined with a thin layer of crystals (an organ called the tapetum lucidum) that reflects gathered light over sensory cells on the retina, thus improving the fish's low-light vision even more. No doubt, these ocular enhancements aid shallow-water sight feeding during twilight hours. I've often caught catfish on lures that produced no scent, sound or vibration, including tiny jigs used for crappie and sponge-rubber spiders intended for bluegills. That's all the proof I need to conclude that catfish have excellent sight despite having tiny eyes.
In extremely turbid waters, acute vision provides few benefits. Where sight distance is less limited, however — in clear water, for example — catfish use their eyes to find food and avoid predators. Anglers who understand this can use it to their advantage to catch more cats.
To purchase an autographed copy of one of Keith Sutton's catfish books, visit his website at www.catfishsutton.com.