January 03, 2012
By Ned Kehde
Back in the late 1970s, young Dion Hibdon's science project spawned a revolution in how bass anglers dressed their bucktail jigs. Hibdon's project revolved around creating soft-plastic replicas of the crayfish that inhabited the Ozarks streams around Versailles, Missouri. Ultimately, the Guido Bug was created, which we have written many words about across the years.
Last year we got wind that Caitlin Young of Blythewood, South Carolina, was working of a science project that would rival Hibdon's. So, we asked her if we could post it on In-Fisherman's blog site. She said we could.
Here's her report:
The Color Preference of Catfish
Muller Road Middle School
Blythewood, South Carolina
My experiment is on the color preference of catfish. Many people think that catfish only feed by touch and smell and are not visual feeders. Channel catfish, however, tend to have good eyesight and can be very visual feeders. I decided to put that to the test. I did some research and found the top four colors that catfish were rumored to like and hand tied flies in those exact colors. The top four colors were black, blue, pink, and chartreuse. I made a chart with three columns and four rows. The rows were for the colors and the columns were for the number of trials. I found The Cohen Campbell Fisheries Center at Columbia, South Carolina, had catfish and the right size tank with good water clarity for me to use for this experiment. They were very accommodating and also very interested in the study I was doing. To their knowledge, no one had done a study like this on catfish. By running each of the flies through the holding tank a set number of times, I was able to determine that catfish do, indeed, have a color preference. They overwhelmingly chose blue, which confirmed my hypothesis. Chartreuse was a close second followed by black and then pink. Even though all of the numbers clearly showed blue as the favorite, I decided to use a spreader bar that had three flies rigged to it just to see if they would still go out of their way to hit the blue one. Even with a chartreuse and pink fly on the outside of the spreader bar and seemingly easier to target, the fish still overwhelmingly targeted the blue fly in the middle. By rigging the two brightest colors on the outside, the fish would have to deliberately target the color in the middle, which they did.
Since the common misconception is that catfish are lazy bottom feeders that only eat food that stinks or that they feel with their whiskers, I thought it would be interesting to see if they actually rely on their eyesight to determine what they're going to feed on. It's been proven that a fish's eye can pick up color; so my experiment was designed to find out how much of a factor color is to their feeding preferences and what color triggers more bites.
This experiment uses four different colors of flies (hook removed) and test them with a group of catfish in a controlled environment. Each fly will be drug through a tank containing several thousand catfish the same number of times, and each time a fish bites it, it will be counted. There are always rumors about which color is the best and which color the fish bite most, but ask four fishermen which color works best, and you'll usually get four different answers. I decided to use science to prove once and for all which color catfish actually prefer.
My hypothesis is that if catfish do have a color preference, then the color will be blue. Based on the research that I did, channel catfish are visual predators. Their eyes focus mostly on greens and blues because those colors stand out in most water conditions. Since blue is the color that disappears last underwater based on my research about the color spectrum underwater, I hypothesize that blue will be their favorite color.
- One fishing pole and reel spooled with four-pound-test clear monofilament line.
- Four flies that I tied myself to make sure they were consistent, one blue, one pink, one green, and one black.
- A 15' x 10' concrete holding tank located at the Cohen Campbell Fish Hatchery.
- Approximately 4,000 channel catfish (based on the count provided by the hatcher manager).
- A wire spreader bar with three attachments for flies.
- A tracking graph and a pencil.
I tied four flies in the following colors; pink, blue, black and chartreuse. I cut the hook points off so I would not hurt the fish.
The first thing I did when I got to the tank was tie a pink fly onto the fishing line and slowly drag the fly through the length of a 15' x 10' tank 15 times, counting each hit and writing down the total number of hits for each run. I repeated this process two more times for a total of three runs. Next, I repeated the entire process with each of the other three colors. I totaled all of the fish strikes for each color to determine the favorite color of fly the catfish preferred.
After everything was totaled, I used the spreader bar to verify the results by putting the least favorite color (pink) and the second leading color (chartreuse) on the outside of the bar and then the favorite (blue) in the middle of the bar. I put the favored color in the middle of the spreader bar so they would have to make an effort to bypass the two brighter colors on the outside. I made one run of 15 passes with the spreader bar and counted the number of times the fish targeted each color. I would take the total number of strikes from the spreader bar results to either confirm or disprove my original findings.
The pink garnered only 119 bites, coming in last place. Black was the second least favorite gathering 137 bites. Black is pretty much a neutral color and most fishermen would have guessed that black would have done better than it did in my experiment. Chartreuse came in a close second with 140 total bites. Based on my research, greens are one of the colors a fish's eyes pick up easily under most water conditions. The blue was the overall favorite color with a total of 153 bites. My hypothesis was fully supported by this experiment. Even though my numbers confirmed that blue was the preferred color, I used the spreader bar to either confirm or disprove my original findings. Even with the two brighter colors on the outside of the spreader bar and seemingly easier to target, the fish still overwhelmingly targeted the blue fly. They hit the blue fly 21 times versus 10 hits on the pink and 13 hits for chartreuse. By rigging the two brightest colors on the outside, the fish would have to deliberately target the color in the middle, which they did. I was impressed that with the three flies that close together that the fish would still go after the blue one. That, to me, really help illustrate the color preference. It would have been a lot easier just to bite either of the two flies on the outside, but they really went after that blue one.
After researching how colors are seen underwater, it makes sense that blue would be the preferred color and they would react to that the most. Blue is the last color in the color spectrum to disappear under water. Blue is also a color found on many of the baitfish that channel catfish feed on like herring and shad. By putting three colors on one spreader bar only inches apart really illustrated the fish's preference for blue, and it surprised me at how convincing it was. After finding that blue doesn't disappear as quickly as the other colors, and eventually seeing that my hypothesis was fully validated by the tests, I think those who thoroughly examine my methods will agree with my conclusions.
An additional note on scent
I did one more test apart from this experiment solely for my own curiosity. Since adding a scent experiment do this one wouldn't work with my science fair project, I had to leave it out of my original presentation. I wanted to see how much of a factor scent was. The scent I used was Pro Cure's Nightcrawler Super Gel. I used the blue fly, since it was the most popular and ran two flies, one scented and one not, side by side with the help of my dad on one rod. Then, I counted how many hits each fly got. The results were overwhelmingly in favor of the scented fly, 135 to 36. Then, again separate from my actual experiment, I then went back to the spreader bar and rigged a scented pink one on the outside, an unscented blue fly in the middle, and an unscented chartreuse fly on the other side. Again, the unscented blue outperformed event the scented pink one. That really convinced of how much of a factor color can be.
My hypothesis was correct and backed up by the data shown in both the single runs and the run with the spreader bar. Chartreuse did come in a close second, which is understandable because it's the most easily seen colors under water. Since red is one of the first colors to fade under water, it made sense that pink was the least popular color because it is so closely related to red. Black is a pretty neutral color, so the fact that it came in a close third to chartreuse was not all that surprising.
There were no problems with my experiment at all, everything went as planned. The people at Cohen Campbell Hatchery were fantastic to work with and very accommodating.
In sum, I have determined that knowing that catfish do actually have a color preference could change the way fishing companies develop and make their products. In addition, it could increase sales in blue baits and flies. This kind of information can also help fishermen pick the right color when they're fishing and increase the number of fish they catch. Fishing companies could also increase sales by a large margin if the production of blue baits are increased and the public is made aware of my findings.
Uwphotographyguide.com: Underwater photography lighting fundamentals. "Which colors disappear first underwater?" Color spectrum by wavelength.
Scuba-tutor.com: Effects of water density on color and water absorption of color. Why some underwater photos seem washed out with blues. This is where I found that that the chart shows that reveals blue shades are absorbed last with reds being the first to be absorbed and disappear underwater.
Midwest Outdoors Magazine, June 2010 issue: "Does Color Make a Difference to Fish?" by Justin Hoffman.
Lane Hite. Hatchery Manager for Cohen Campbell Fish Hatchery. Explained his theory of which colors the fish respond to best. His actual pick was the Pink one based on personal fishing experience.
- Caitlin Young standing on the tank where she conducted her research.