Fisheries biologists say that color is sometimes the worst way to distinguish one fish species from another. For various reasons outlined below, there are times when even big channel catfish like this one have a color similar to a blue catfish. Photo by Brad Durick
Channel Cats vs Blue Cats: Know the Difference
by Capt. Richard Simms
I have no pride so I’m going to tell a story on myself.
When I saw last month’s CatfishNOW article (and photos) by Capt. Brad Durick about fishing for channel catfish in the Red River, I was certain there had been a mistake made.
I’ve been a hardcore catfisherman for 30 years and a catfish guide for nearly 20 years. I knew (or believed) the lead photo in Durick’s August article was a mistakenly published photo of a blue catfish.
A healthy channel cat taken from the Red River by one of Capt. Brad Durick’s clients. It might look like blue cat on the surface, but Durick says there are no blue catfish in the water he fishes. (Photo: Capt. Brad Durick)
I texted Editor Keith Sutton about what I thought was an error. Keith replied, “No, there are no blue cats in the Red River of the North.”
I was somewhat embarrassed, certain that the striking blue color of the fish pictured meant it had to be a blue catfish. My error inspired me to give myself a refresher course on the scientific ways to tell the two species apart.
On my home water, the Tennessee River, we have both blue cats and channel cats. I frequently have clients who have a difficult time distinguishing the two species, especially when the colors are similar (as in Brad’s photos).
The truth is, and fisheries biologists will tell you, coloration is sometimes the worst way to tell one species from another. There are huge variances in fish colors. Locations, depth, water clarity, seasons and sex can create a wide spectrum of colors, even among the same species. No doubt most of you have put fish in a livewell, yet when you take them out an hour later, they have changed colors dramatically, almost like a chameleon.
It is true that usually it is easy to tell a channel cat from a blue by color. On the Tennessee River, besides being smaller (on average), channel catfish are often an almost brilliant golden color, while blue catfish are, indeed, blue.
Capt. Richard Simms guides for catfish on the Tennessee River. He says on that river, the different color is almost always a dead giveaway of which species his clients have caught (top, blue catfish – bottom, channel catfish). Simms says, however, there are times, especially with larger channel cats, that the color can be surprisingly similar to a blue.
But sometimes, especially with larger, older channel catfish, the color can be similar. So here is how you definitively tell channel cats from blues, the scientific way.
Channel Catfish:
- Scattered black spots on the back and sides, especially on younger fish
- The outer margin of the anal fin is rounded outward (convex) rather than straight
- The most definitive difference is that the anal fin has 24-29 rays
Blue Catfish:
- The blue catfish never has dark spots on the back and sides
- Blues have a straight-edged (not rounded) anal fin
- Blue catfish always have 30-35 rays in the anal fin
So, some differences might be hard to notice, but if you need to settle a bet, count those anal rays.
On a channel catfish, the anal fin has a curved (convex) shape and always has 24-29 rays.
On a blue catfish, the anal fin is basically straight-edged and always has 30-35 rays.
(Capt. Richard Simms is the Editor of our sister magazine, CrappieNOW, as well as owner of Scenic City Fishing Charters. He is a former game warden for the Tennessee Wildlife Resources Agency before becoming a photographer and PR guy for TWRA. That led to a 30-year career as a broadcast journalist and freelance outdoor writer. You can follow Capt. Simms on Facebook or contact him at Richard@ScenicCityFishing.com.
