Carpsucker anatomy

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Conecuh's picture
Carpsucker anatomy
<p>I snagged this quillback while fishing over groundbait today.</p> <p><img alt="" src="" style="width: 800px; height: 455px; " /></p> <p>I was psyched when I first got him in because it looked ike the hook was in the mouth. But it turned out to be through the bottom of the lower lip. He went home with me anyway, so I could see what he&#39;d been eating, and to see how carpsucker tastes.</p> <p>&nbsp;</p> <p>It was 15 and a half inches long and weighed 1 lb. 10 oz</p> <p>&nbsp;</p> <p>Carpsucker lips extended, foraging.</p> <p><img alt="" src="" style="width: 720px; height: 466px; " /></p> <p>Carpsucker lips a split second after it detects a hook in it&#39;s mouth (I would think).</p> <p><img alt="" src="" style="width: 720px; height: 482px; " /></p> <p>This guy could retract his lips an inch and a quarter. My hook would be somewhere down at the half inch mark, just drifting in the open water.</p> <p>&nbsp;</p> <p>Inside its mouth was a cavity that could hold a walnut. I imagine all the water in its mouth can be expelled quickly when it detects something in its lips it doesn&#39;t want there.</p> <p>&nbsp;</p> <p>This was the majority of the contents of (what I took to be) its stomach and upper intestine.</p> <p><img alt="" src="" style="width: 640px; height: 458px; " /></p> <p>Its initial digestive organ, I guess its stomach, but more like a gizzard really, was about the size of its eyeball and had openings on both ends of just millimeters. Its stomach and upper and lower intestines would all fit in the volume of a golf ball. The air bladder, milt, and liver took up the vast majority of the body cavity.</p> <p>&nbsp;</p> <p>The largest and most identifiable items in its digestive system were the little grains of cornmeal from the chicken feed groundbait. The rest was just an unidentifiable mixture of bottom ooze and algae. No apparent critters. So scratch my theory about them hunting little organisms in the groundbait. They just eat very little, very slowly.</p> <p>&nbsp;</p> <p>I&#39;m interested to see how it tastes. It&#39;s on the menu for supper tomorrow.</p>
Conecuh's picture
Carpsucker is good. Flaky

Carpsucker is good. Flaky white flesh, delicate flavor, not oily, no muddy or "fishy" taste.

Dr Flathead
Dr Flathead's picture
They still could be insect

They still could be insect eaters.  I bet they do at least on occasion.  Carpsuckers have really keen eyesight.  You cant tell me thats just used to hunt down bottom ooze.  And maybe their digestive juices just break stuff down extra quick?  So much is unknown about them still. 

TonyS's picture
I'd bet they are eating bugs

I'd bet they are eating bugs as well (and algae and random junk) - but I bet they are damn tiny bugs.  The numbers of tiny bugs under a couple milimeters is probably enough keep them busy.  Honestly some of those bugs are hard to see as is - I imagine they'd digest fast.  Most of the stomach contents of the Round Whitefish I disected last spring was "ooze" there was no algae to graze on so I'm sure that ooze could be digested bugs and "non-food" ingested along with the food


TheHugbot's picture
I could be bits if digested

I could be bits if digested bugs with debris and sediment from the riverbed mixed in, from what I've heard they seem to suck up substrate and filter out food, so there could be some sediment in their gut. 

Gunnar's picture



Redhorse ID cheatsheets, gars, suckers:

2020: 10 days fishing 11 species 0 lifers. 2019: 34/45/13 2018: 39/40/5

Conecuh's picture
Oh yeah, they definitely do

Oh yeah, they definitely do eat bugs. My original theory about them hunting bugs in the groundbait came partially from this paper:

Page 45 has an interesting table of what was found in the stomachs of various sucker species.

I'm sure if there happens to be any bugs around the groundbait, the carpsuckers would eat them, but 2 things have me doubting my original theory.

1. I'm now not certain the groundbait actually attracts a lot of bugs.

2. The carpsucker I dissected was clearly feeding on little pieces of the groundbait.

If anything, they're attracted to the whole enchilada, groundbait+bugs.

I could make a bug trap, bait it with groundbait, and see.


While bottom fishing blind without a float (which I don't think is a viable option), I found out these three things.


1. Freshness of bait matters quite a bit. A piece if worm that had been cast several times and had most of its scent washed away was ignored. A fresh piece of worm got more bites. This actually does back up the little critter theory: They prefer fresh meat.


2. Size matters. A size 24 hook got more bites than a size 18.


3. Visibility matters. Just downstream from the groundbait, it was deeper and murkier. I could just barely make out the shapes of quillbacks feeding there. I got more bites in general, and on the bigger hook(#18), in that poorer visibility hole. I also got more bites in the evening, as the light was failing. If they can't use their eyesight, they will still feed, apparently.


Also, I think the "bites" I was getting was their blowback mechanism. The actual take can probably only be seen with a very sensitive indicator (like a well balanced float). Their blowback is probably much more forceful. Which explains why no matter how fast I tried to set the hook, I never got anything. The hook was already out of their mouth by that time.


Gunnar's picture
Also, I think the "bites" I

Also, I think the "bites" I was getting was their blowback mechanism. The actual take can probably only be seen with a very sensitive indicator (like a well balanced float). Their blowback is probably much more forceful. Which explains why no matter how fast I tried to set the hook, I never got anything. The hook was already out of their mouth by that time.

That's what I've always believed is happening when I've felt but failed to hook quillbacks.


Redhorse ID cheatsheets, gars, suckers:

2020: 10 days fishing 11 species 0 lifers. 2019: 34/45/13 2018: 39/40/5

atenkley's picture
Good Stuff Here!

.....getting motivated to apply what is being learned.  I have not targeted Carpsuckers yet.


....visit  .....those other fish

Tyler W
Tyler W's picture
Naked Eye

It can be tough to clearly spot inverts with the naked eye, but I would expect you to notice some critters or parts of critters. I know I can see bugs as small as 250um with the naked eye. Although stomach contents should be somewhat broken down I have looked at many stomachs where I could reliably identify plankton to species. If individual bugs make up a large portion of their diet, parts of them should be visible. 

This discussion has largely considered diet as bugs vs algae. But, there is a third way: aufwuchs.

Aufwuchs is a handy German word that loosely covers algae and the bugs that live in that algae that are too small to separate from the algae.  Looking at the diet table (pg 45) 77.1% of their diet (%SA) is chironomids and oligachetes.  Those are bugs that would be present in the "auwfuchs". Bugs as big (and mobile) as a mayfly larvae were only 0.6% of their diet. 


From all of this, I think that carpsuckers probably graze on the best tasting aufwuchs they can find. I doubt they spend very much time eating individual bugs like a redhorse. But, by choosing the thickest and best tasting algae films... they also select for chironomids and oligachetes in their diet. That would also explain why they like chicken crumbles - it is basically an instant auwfuchs. With its high protein content and soft texture it probably tastes really good to carpsuckers, even though the crumbles don't look like bugs at all.


Eric Kol
Eric Kol's picture
aw f**ks is about right!

aw f**ks is about right!

Carpy Diem!

Dutch's picture
Also, I think the "bites" I

Also, I think the "bites" I was getting was their blowback mechanism. The actual take can probably only be seen with a very sensitive indicator (like a well balanced float). Their blowback is probably much more forceful. Which explains why no matter how fast I tried to set the hook, I never got anything. The hook was already out of their mouth by that time.

You say you think the bite you feel are from the blow back, I wonder if a mini hair style rig with a small piece of crawler on it would help you get the hook up?

Conecuh's picture
I've recently groundbaited in

I've recently groundbaited in clear waters and found a few things out, most of which are not encouraging.


Most of the carpsuckers are highfins, not young quillbacks like I had first thought. A ratio of robably 5:1. I don't know how that would be in the midwest, especially when you throw river carpsuckers into the mix.


Most of the "bites" I've felt are actually their fins brushing the line. Kind of embarrassing to realize this. It would account for why it happens more in low visibility conditions. As far as fresher bait getting more bites, that's probably just confirmation bias on my part. I do think that the bigger quillbacks might occasionally bite on a piece of worm. Hard to tell with all the little highfins swarming around, though.


With a larger hook (#8), the quillbacks will get snagged in the outside of the lips, so they might be messing with the worm when that happens. I've never snagged a highfin in the lips, even though they are much more common.


Carpsuckers that have been baited in the same place for several days will start to be your pets, and come running when you throw in the chicken feed. In a good spot, over a hundred carpsuckers will be attracted to several days baiting.


They do not appear to eat a whole layer crumble, just the particles that dissolve off. And when they're homed in on that, that's all they will eat. In clear water, thay will not touch tiny pieces of worms, or even tiny layer crumble doughballs. I haven't tried waxworms or maggots, as they're not easily come by in my neck of the woods.


After observing all this, I think Tyler's hypothesis about the aw f**ks is probably accurate.


Tyler W
Tyler W's picture
Hate to be right

That all makes sense, but I wish it wasn't true. I wonder if there is anything you can do to the groundbait to encourage them to eat the hook baits. I know Matchman would order huge numbers of waxworms (from Vados Bait) to put in his groundbait. Trying that with carpsuckers might just turn the swim into a sunfish orgy. But, maybe larger harder to eat crumbles would make the carpsuckers more willing to eat a worm. 

I am also wondering about using a presentation that meshes better with their delicate feeding. If they are feeding by gently vacuuming particles from the layer, maybe the bait needs to be neutrally buoyant. Anchor Tackle makes double cut split shot as small as 0.01 grams... maybe a tiny pop up rig would give the bait the right feel. A size 24 hook, a wax worm (inflated with a worm blower?) and one or two #13 split shot 0.25" from the hook, then a 6" leader to a fixed lead. A micro pop up rig.... 

"Line bites" are part of the game, especially when fishing in schools of fish. I wouldn't consider that embarrassing, it is just the nature of the beast. 

Good luck. And thanks again for sharing the details of what you have seen. I think we are all learning from your experiments. 

Muskymags's picture
Time of year, clarity?

I, as many hear have caught them on crawlers.  They eat bugs at other times...... John at Currents ( has had great success in Iowa flyfishing for them (search Quillback on his blog!).  Not sure if theres a pattern, just the day, time, hour, minute preferances for individual fish.  I love pizza, mexican foods, and pasta; but every so often I get a craving for salad.   I think Carpsuckers are the same.......picky eaters and depending on the locale and the mood of the fish, greatly depends on the success of the angle.  I don't think anyone could ever go out and "hammer" the Carpsucker, catching many.  1,2, MAYBE 3.....They are just more picky than other fish?

Tyler W
Tyler W's picture
Seen them caught

I have seen Avidfly fair catch at least three in one session. I know it is possible. But we all know it is not possible every day (they aren't bass!). On the good days they are still focused on the algae and microscopic bugs... if they actively hunted larger bugs we would catch them as easily as shortheads. Will they eat a worm? Absolutely. Particularly if it is laying on a nice piece of algae.

I think Conecuh's observations mesh well with my own. i.e. They prefer grazing over hunting.

But, sometimes they prefer being hit in the face with a wooly bugger....

Hengelaar's picture
Cutting Edge Stuff

It's great reading all this field research.

But man... It just seems like a miracle that any of you ever catch any of them!

What hope have I, then..? 

Some. I have some.

Fishn sure is neat

andy's picture
All of this awesome scientific conjecture...

It's all fantastic.  The feeding habits of carpsuckers are so perplexing.  Groundbaiting, subtle baits, light lines and playing the odds...we can dissect them to determine stomach contents, sit for days without bites... and only occasionally does a good angler actually target them by sight-fishing and have one suck up your offering and fair catch one.  Many times we land them only to find our tiny hook is embedded just outside the lip.  Better set the hook in a flash then, before they spit it out.  Man, what frustration!

They are an admirable challenge for those of us who wish to figure a species out.

Or, you could simply stab one in the face with a size 2 wooly bugger...that works too.  I hear dardevles work pretty good, but I know that guy is a flyfisher and is above that!

Dr Flathead
Dr Flathead's picture
I too watched the great

I too watched the great eyeball himself Avid catch 3 in a session.  And it was, of course, in that one special place where we have done the best.  Seems like their more apt to take a crawler chunk back there for some reason.  And they were taking it right off the sand, nothing else around that you could see with the naked eye from the boat.  I got one that day too, fairly in the mouth.  So that was pretty much "hammering them" in my opinion.  I have had no other sessions on any other bodies of water that were like that day.  Except one time when I got two in one day, back to back on a half crawler.  That was like the twilight zone of carpsucker fishing. A complete fluke.  Not out of the special spot either.  Both sight fished.  Both fish eagerly ate it too.  But there was a bunch of them there that day.  Had tons of other situations like that day, none of them ever panned out like that.  I've hooked probably a half dozen around the mouth, more than I've caught fairly.   


I'm gonna try this groundbaiting of waxworms and gardenworms out here this next summer.  My targets will be mostly highfins and rivers, but will try it on pods of quillies too.  Quillback are the most commonly sighted carpsucker around here in MN.  I have been introduced to areas where its not uncommon to have a half dozen or dozen grazing the bottom at all times in clear water.  Easy sight fishing water.  Quite frankly, I'm sick to death of presenting a hunk of crawler or redworm to them, without the benefit of setting the table ahead of time.  They burn me out way too quick anymore.  I need new tactics like this groundbaiting and chicken feed layer stuff.  Now I'm all excited to try this out here going into December.  Thanks guys! 

Corey's picture
Great research

Love to see some people aggressively attacking this problem.  Just to add my own ideas (most of which I've already mentioned elsewhere) ...

From studying Becker - he posits that carpsuckers feed on whatever food is abundant.  If the area has millions of midge larvae, then you'll find millions of midge larvae in the stomach.  Sometimes, it''s just algae and ooze.  Take that how you like.  From Lizzy Stull, match fisher who groundbaits with gallons of maggots, she calls them "Breath Feeders" who use the jet of water in their mouth to feed.  She uses split-shot the size of pepper grains leger-rigged and a very sensitive float.  She doesn't have them figured out, but they do take a maggot for her sometimes down in Chicago.

Chumming with corn, sometimes they'll take a single corn kernal.  I think most of the time when you catch them blind-fishing with a crawler or corn, they're sucking it in to taste it and then get hooked while trying to expel the bait.

From flyfishing for them a lot, I can say it's very easy to snag them near the mouth.  Fly tackle is really perfect for snagging - and the fish snagged while flyfishing do not help to explain the mystery.  If they take the fly, it would be carried deep into their oral cavity by the mouth suction.  I've never seen that.  All the people I've seen get them on flies are snagging them.  You'd always hook them on the interior of the mouth if they were taking the fly.  Physically, though, they can't intercept a drifting fly because their mouth extends straight down an inch below their head, like a sturgeon.  They feed on stuff that's stationary and right below their nose, very gently inhaling it. 

As the guy said, the entrance to the stomach is millimeters in size.  They're not chasing down crayfish.  Most mayfly larvae are too big. 

They respond to groundbait, but it takes awhile.  It's uncertain exactly how or why. 

They have big eyes, but I don't think they feed by sight.  It is impossible to sneak up on them.  They use their excellent vision to avoid predators while they feed in shallow water.   

I have witnessed a lot more success with single baits while fishing over sand.  This dovetails with some of my observations about shorthead redhorse.  Sand is a barren desert for fish-foods - meaning the fish need to be more aggressive in finding things to eat when they are over sand.

All of this is speculation, obviously - lots of guys on this site know a lot more than I do about them. 


Jknuth's picture
Awesome observation about the

Awesome observation about the sand. 

Nearly all of my carpsucker have come on the sand flats on the wisconsin river. Or similar rivers. 
I have caught a few on small crappie minnows that were quite dead and mashed below dams in the early spring. And two at the roundup in the middle of the night in a deep rocky pool. But the rest were over sand. And by sand I mean barren sand wastes with no cover rocks pebbles nothing.

Here is one I got this summer with Roughie

here he is swimming away. 
When he hit the bait his dorsal was out of the water and he was laying at an angle slowly working the shallows along with several dozen other fish. Probably in 8" of water


Outdoors4life's picture

It is a fine line!

I have caught some real nice ones and sight fished every one of them. Many times I have snuck up on them and have learned how to tell when they are feeding and when they are not. If they are not feeding actively I do not even fish them.

If you sit and watch them long enough it seems as though there are feeding lines that they follow and I can not see why but do pay attention to them. Like I have said for a few years it is a Love-Hate relationship with them. It is cool to show myself that I can catch them but I hate getting skunked by them.  Many times I have thought of baiting them but I think this is the year to do it. Well 2013 that is.

It is all perspective!

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