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Exploring the Fascinating Life History of Sculpin: How to Imitate Them with Flies for Trout Fishing Success

My favorite fishes are sculpin, other than maybe Brook Trout. They are just such cool fishes! I hope to persuade you of their "coolness" by the end of this post. And then give you some ideas on how to imitate them in your streamers. (Can you tell that it is an AI title?)

Slimy Sculpin from Monroe County, WI
That classic sculpin look - a big head and pectoral fins and a camouflaged body tapering down the tail. They are evolved for a benthic life style.

Before graduate school, I certainly knew that sculpin existed as do pretty most all fly anglers but I can't say that I knew a lot about these cool little fishes. I left for West Virginia for graduate school to work on a small stream research project that didn't work out for reasons I'll share over a campfire sometime. So my Masters research ended up being on the Ohio River, a rather sculpin-free place. However, in my Ph.D. research in the Cheat River watershed, we captured over 100,000 Mottled Sculpin (Cottus bairdii). And capture probabilities for sculpin are really low (Hense et al. 2010, Ruetz et al. 2015), after all, they are evolved to be the ultimate benthic fish. They were by far, and it is not even close, the most abundant fish species in our research in the Cheat River watershed. My Ph. D. advisor did his Masters and Ph.D. on Mottled Sculpin (Petty and Grossman 1996, 2004, 2007, Grossman et al. 2006) so sculpins are certainly in my academic DNA.

All About Sculpin: Evolution and Life History

Sculpin have marine roots, though today many sculpin species occur in freshwater lakes and streams. Some species have both fresh and saltwater populations - which is quite a rarity among fishes. As with bird books that tend to be organized according to evolutionary origins, in which the "oldest" taxa coming first, sculpin - order Scorpaneniformes - are listed last in Becker's Fishes of Wisconsin book. Sculpin are relative newcomers - but fishes are quite old as a taxa. The center of diversity for sculpins is the northern Pacific Ocean, meaning that they widely distributed in much of the northern hemisphere.

The video above is Avery Lettenberger's 2024 Driftless Symposium talk about his research on sculpin's ability to swim on different substrate types.

The Ultimate Benthic Fish

Sculpin have evolved to live a benthic (bottom-dwelling) life style. This is evident in their hydrodynamic shape, their lack of a swim bladder, camouflaged coloration, and those notably large pectoral fins. All of these characteristics may not make them the "perfect" benthic species - evolution does not strive for perfection - but they are well suited to living on the bottom of streams, lakes, and the ocean. I would say they are better suited than any other taxa to a benthic lifestyle. It's a pretty successful body plan!

As you probably know, the swim, air, or gas bladder - whatever you want to call it - is an adaptation to assist fish with buoyancy. Being benthic specialists, buoyancy is not a characteristic that is adaptive so sculpin have lost their swim bladders. But probably the greatest adaptation to their benthic life style is their shape and those unique pectoral fins. Because they are so uniquely shaped, plenty of research has been conducted on how their shape affects their ability to live in and amongst the rocks along the bottom (Coombs et al. 2007, Kane and Higham 2012, watch Avery's Driftless Symposium talk, embedded above).

Slimy Sculpin close-up
Zoomed in on a Slimy Sculpin.

Sculpin live on and under the rocks in streams so they are quite susceptible to the effects of sedimentation (more on that later...). They not only live under the rocks but they have adhesive eggs that they stick to the bottoms of the rocks they often live under. They will also use aquatic vegetation to create nests for spawning. They are quite territorial (Petty and Grossman 2004) and the patches that they defend are determined largely by access to their insect prey (Petty and Grossman 1996). I could continue to write about all the cool things sculpin do and what makes them unique but I will spare you.

Sculpin in Wisconsin

There are nearly 400 species of sculpin in seven different families; the vast majority - about 275 species - belong to the family Cottidae. This family consists of both freshwater and marine species with most of the freshwater species belonging to the genus Cottus. This includes the two species we find in Wisconsin streams - Mottled Sculpin (C. bairdii) and the very poorly named Slimy Sculpin (C. cognatus). They are quite difficult to tell apart. We identify them by pelvic fin ray counts (3 in slimy, 4 in mottled), whether the last couple of anal and dorsal fin rays are forked or not (they are in slimy but not mottled), and Slimy Sculpin lack the palantine teeth (tooth patches in their mouths) that Mottled Sculpin possess. Though for most of these differences, Becker (1983), in his Fishes of Wisconsin book, says "usually" which means their characteristics overlap significantly. It is assumed that the maps below have some identification errors in them. Deepwater Sculpin (Myoxocephalus thompsonii), another species that occurs in Wisconsin, are found in the Great Lakes and I will largely ignore them here.

Mottled Sculpin distribution, Source: Becker - Fishes of Wisconsin (book)

Slimy Sculpin range map. Source: Becker - Fishes of Wisconsin (book)

As you can see from the maps from Becker's Fishes of Wisconsin, Mottled Sculpin are more widely distributed. Slimy Sculpin prefer colder streams than do Mottled Sculpin and are a glacial relict in Wisconsin. This might explain their distribution in the Driftless, the two Great Lakes, and a number of Lake Superior tributaries. As mentioned previously, there is a pretty good chance that the two inland species have been misidentified in the past. We don't know a ton about the distribution in the Drifless Area - hopefully our grant application is funded and we are able to learn more about their current distributions in the Driftless Area.

Examing slimy sculpin
Capturing and examining Slimy Sculpin to be reintroduced into southern Crawford County streams (photo from Kirk Olson)

I suspect that Slimy Sculpin are missing from a large part of their original native range in the Driftless Area. Being susceptible to the effects of sedimentation is not a trait that is conducive to survival in a region where the valleys and their streams were filled with several to many feet of "cultural sediment". While I have heard some say it was due to Wisconsin DNR eradication efforts, the scale that they would have had to occur over are just not feasible. Whereas the cultural sediment issues occurred over the entire Driftless Area and is a much more logical explanation. The Driftless Area of today is much improved over its historic condition.

Reintroducing Slimy Sculpin
A couple of hundred Slimy Sculpin being released into their new home (photo from Kirk Olson).

I suspect that invasive Brown Trout, which are highly piscivorous, have had quite an effect on sculpin as well. There are still some strongholds for Slimy Sculpin - particularly on and around Fort McCoy. I have to wonder if the lack of agriculture in those watershed have allowed Slimy Sculpin to persist. Fort McCoy was created in 1909 which predates some of the worst sedimentation rates in the Driftless (Trimble 1983).

Slimy Sculpin
A slimy sculpin that is going to be moved to a new home to reestablish a new population in their native range (photo from Kirk Olson).

The Wisconsin DNR is reintroducing Slimy Sculpin to part of the Driftless Area native range in hopes of boosting their range to something closer to their historic range. This is particularly true now that our streams are in much better shape then they were 50 or more years ago. It will be interesting to see how they fare in places they were had been extirpated.

Imitating Sculpin

There is no shortage of choices for flies that imitate sculpin. What I want in a sculpin pattern is some weight to get it down, a big, water-pushing head, and an upward facing hook so the fly can be swam / bounced along the bottom of the stream without snagging bottom. These can range from quick and simple flies to quite extravagant flies that take 20, 30, or more minutes to tie. To be honest, that is not the sort of time I want to put into a fly that I want to fish along the bottom of the stream. Of course, the original Muddler Minnow was designed as a sculpin imitation and does match some of the things I am looking for in a sculpin imitation. I generally prefer muddlers as flies fished in the water column. The following are previous posts on muddlers and variations of them.

Dave Whitlock's Near 'Nuff Sculpin is about as simple a version as there is. And it is a great option that ticks most of the boxes of what I am looking for in a sculpin pattern. It is essentially a modified Woolly Bugger so it is relatively quick and easy to tie. Dave Whitlock offers some other sculpin options and how to fish them in his article, Dave Whitlock's "Fishing Sculpins".

Cheech and the gang at Fly Fish Food have a significant number of sculpin pattern videos. Probably my favorite style of sculpin patterns is the "slider" style. Sliders are significantly weighted, they allow for a large, water pushing head, and the buoyancy of the deer hair is more than offset by the weight. And they are relatively easy to tie - just keep the hair that makes the collar from spinning!

Below is one version of a sculpin slider I have tied. I use a little more marabou as it moves nicely in the water and because how I tie it as a palmered hackle, when wet, it will provide the quintessential sculpin body taper.

Below is another version of a slider with some pectoral fins added. With all my sculpin imitations, I prefer that a bit of that lighter underbelly showing through. As mentioned above, sculpin - like nearly all aquatic organisms - are countershaded with lighter bellies and darker, more camouflaged dorsal surfaces.

Another slider variation
Another version of a slider pattern - this one with barred olive zonker strips for the pectoral fins and to add a bit more bulk "up front". I use the underside view as you can see the fins best.

Getting a little more local, this is a fly tied by Nick Pavlovich for Black Earth Angling Co.'s "Drinking with Scissors" fly tying series, the Kamikaze Sculpin.

Another great way to get the fly down are Flymen Fishing Company's Fish-Skull Sculpin Helmets. And barred zonker strips are another great way to imitate the dorsal mottling of sculpin. The Mohawk Sculpin 2.0 gets a little more complicated and specialized with the Kiley's Fish Finz.

The Sculpin Toad is another FlyFishFood pattern which is a fun and interesting pattern to tie. I've found the work better is slower water where they are really good at staying on the bottom and moving like a benthic fish does.

To add an articulated option, Brammer's Sculp Daddy is mostly marabou and streamer dubbing. While there is a lot to it, it is not an overly difficult fly to tie. It is more of a swimming fly - note the downward facing hook.

Lastly, as we ramp up some of the more complex and involved sculpin patterns, of course we can use a "game changer" style fly. It is a pretty good option for sculpins as game changers are designed to have a nicely tapered body. And, as you've seen in the photos above, sculpin are a strongly tapered body plan.

Moving back towards simplicity, the jig streamer style is not one I have fished much but they tend to be quick, simple streamers that are aimed at getting down quickly. I think anyone can tie this fly.

Lastly, I will share more more style of flies for sculpin, more of a swinging style fly. I share this as it is something different. Swinging sculpin is not something I am terribly familiar with but I'd certainly be happy to go try it in Alaska. I typically want my sculpin ticking along the bottom, the thought being that their movement is what triggers trout to bite. Often sculpin are eaten by fishes when they "give themselves up" and move. Camouflage is their greatest defense.

That is but a small sample of the different ways you can tie sculpin patterns. They tend to be cryptically colored so sculpin in weedy streams are more olive and those in and among rocks more brown and tan. I tie most in olives and brown shades, often mixing the two into olive-brown patterns for Driftless streams. I like barred materials for tying sculpin to make them more realistically colored. And again, I want the bottom of the fly to be a little lighter colored and maybe a bit flashy.

The options of fly patterns gives some perspective on just how important sculpin are for the fly angler. They exist more or less from coast to coast and in warm and cold waters. Imitations should certainly be in your fly boxes!

Links to Sources of Information

OK, one more fly pattern - how can you not include Sculpzilla?

Literature Cited

Becker, G.C. 1983. Fishes of Wisconsin. University of Wisconsin Press, Madison, WI. 1052 pages.

Coombs, S., Anderson, E., Braun, C.B. and Grosenbaugh, M., 2007. The hydrodynamic footprint of a benthic, sedentary fish in unidirectional flow. The Journal of the Acoustical Society of America, 122(2), pp.1227-1237.

Grossman, G.D., Ratajczak Jr, R.E., Petty, J.T., Hunter, M.D., Peterson, J.T. and Grenouillet, G., 2006. Population dynamics of mottled sculpin (Pisces) in a variable environment: information theoretic approaches. Ecological Monographs, 76(2), pp.217-234.

Hense, Z., Martin, R.W. and Petty, J.T., 2010. Electrofishing capture efficiencies for common stream fish species to support watershed-scale studies in the central Appalachians. North American Journal of Fisheries Management, 30(4), pp.1041-1050.

Kane, E.A. and Higham, T.E., 2012. Life in the flow lane: differences in pectoral fin morphology suggest transitions in station-holding demand across species of marine sculpin. Zoology, 115(4), pp.223-232.

Petty, T. and Grossman, G., 1996. Patch selection by mottled sculpin (Pisces: Cottidae) in a southern Appalachian stream. Freshwater Biology, 35(2), pp.261-276.

Petty, J.T. and Grossman, G.D., 2004. Restricted movement by mottled sculpin (Pisces: Cottidae) in a southern Appalachian stream. Freshwater Biology, 49(5), pp.631-645.

Petty, J.T. and Grossman, G.D., 2007. Size-dependent territoriality of mottled sculpin in a southern Appalachian stream. Transactions of the American Fisheries Society, 136(6), pp.1750-1761.

Ruetz III, C.R., Harris, B.S., McNair, J.N. and Homola, J.J., 2015. Removal and Mark–Recapture Methods for Estimating Abundance: Empirical and Simulation Results for Mottled Sculpin in Streams. North American Journal of Fisheries Management, 35(1), pp.62-74.

Trimble, S.W., 1983. A sediment budget for Coon Creek basin in the Driftless Area, Wisconsin, 1853-1977. American Journal of Science, 283(5), pp.454-474.

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So, you like them brown-olive with a lighter bottom. I don't see any of these that do anything to achieve the latter. So which of the above do you usually tie and how get the lighter bottom?

Replying to

Brian, most of them I tie at least have something white - diamond braid, small sparkle chenille, ice dub - around the hook shank. The sliders I tied above all have diamond braid and one them them has a bit of streamer dubbing as a "throat". It's not as visible as when all that marabou and/or zonker strips are wet. My "go to" is probably a slider or flies tied with the "Sculpin Helmet". On both of them, the easiest way to get a lighter underbelly is to tie in a length of streamer dubbing (long-fibered dubbing) just behind the dumbbell eyes or "helmet".


Jason, if you look closely at George C. Becker's Wisconsin map for slimy sculpin the main concentration of slimy sculpin is in Timber Coulee Creek and tributaries of Timber Coulee. Palmer Olson released a lot of Brown Trout fry hatched from Brown Trout eggs from the Brule hatchery into Timber Coulee and Timber Coulee tributaries.. No written records but my guess the slimy sculpin in Timber Coulee was transplanted from the Brule River by Palmer Olson. A side story, some people were netting baby brook trout and sculpin in the Little Plover River and putting them in a 5-gallon bucket. Later, when they looked in the bucket all they could see was a happy sculpin with a belly full of…

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