Chasing the Fish of 10,000 Casts

About a month ago, I emailed a friend a photograph of the impressive Lake Sturgeon I had caught with a guide on the Mississippi River in mid-July.

His response was immediate:

“Fun to catch, but damn are they ugly fish!!!! You should try a muskie guide on Leech Lake.”

And so I did.

The muskellunge, or muskie (Esox masquinongy), is the largest member of the pike family and one of North America’s most sought-after freshwater game fish. Often called the “fish of 10,000 casts,” muskies are relatively rare and notoriously difficult to catch. As apex predators, they can exceed 50 inches in length and weigh more than 40 pounds in Minnesota waters.

After a little research, I booked a guided trip with Luke Swanson of Livin’ the Dream Guide Service. I also invited my friend Jesse Hoekstra, a family friend and work colleague, and his son Briar to join me.

I drove to Brainerd the evening before and spent the night at a Holiday Inn Express. My alarm went off at 4:45 a.m. so I could meet Luke at Alexander Lake, about thirty minutes southwest of Brainerd, at 6:00 a.m.

Unfortunately, the day got off to an inauspicious start.

About five minutes from the landing, a deer suddenly darted into the road. I had no time to avoid it. The collision completely destroyed the front bumper of my car.

I pulled over to inspect the damage. The bumper looked terrible, but the vehicle appeared drivable. Since there was not much I could do about it before dawn, I climbed back in and continued toward the lake.

When I arrived, Jesse and Briar were already in the boat with Luke.

“Sorry I’m late,” I said. “I hit a deer about five minutes back.”

They expressed their sympathy, and we all agreed that the bumper could wait until after the fishing trip.

We had muskies to chase.

Luke was a friendly and colorful character who looked to be in his mid-thirties. He explained that he spends June through December in Minnesota and January through May in Florida near Fort Myers. During the Minnesota season he guides for muskies, walleyes, and smallmouth bass. During the winter and spring he guides primarily for tarpon in Florida.

According to Luke, tarpon are the greatest fish in the world to catch.

“Nothing else compares,” he told us.

The weather was pleasant for late August, about 60 degrees with mostly cloudy skies and only a light breeze. It felt a little chilly at first, but it warmed steadily as the morning progressed.

Luke supplied all the rods, reels, and tackle. Our first lesson involved learning how to cast and retrieve muskie lures. These were not the tiny spinners and jigs I was used to. Most were eight to ten inches long and looked more like small fish than lures.

Luke also taught us the famous figure-eight maneuver beside the boat. Apparently, muskies often follow a lure all the way to the boat without striking, and abruptly lifting the lure from the water can cost an angler a fish. Instead, experienced muskie anglers sweep the lure in large figure-eight patterns next to the boat in hopes of provoking a last-second strike.

After about thirty minutes of practice, Luke showed us the technology that would help us find fish.

His Garmin sonar unit was astonishing. It scanned far ahead of the boat and well off to each side, allowing him to locate schools of baitfish and, occasionally, the large predators we were seeking. As we cruised around the lake, he pointed out schools of perch and crappies on the screen. Every now and then a much larger mark would appear.

“That’s probably a muskie,” he would say.

When Luke spotted a fish he liked, he would quietly maneuver the boat to a position about fifty feet in front of it. One of us would move to the bow and cast toward the fish while Luke monitored its movements on the sonar.

Then the coaching would begin.

“Twitch.”

“Pause.”

“Speed it up.”

“Now slow it down.”

Everything depended on how the muskie reacted.

We rotated turns, and Briar was first up.

After about thirty minutes of searching, Luke spotted what he felt was almost certainly a muskie. Briar stepped to the front of the boat and made his cast.

Then, seemingly within seconds, he hooked a fish.

“Keep reeling!” Luke shouted. “Don’t stop reeling!”

Briar followed instructions perfectly.

I don’t remember exactly why continuous reeling was so important, but Luke made it very clear that stopping was not an option.

After a short but spirited fight, the fish came alongside the boat and Luke skillfully netted it.

We had our muskie.

The fish was a solid muskie and a beautiful fish. Briar had landed a muskie, and that was cause for celebration.

Jesse, Briar, and me with Muskie

Luke took several photographs: Briar alone with the fish, Briar and Jesse together with it, and one with all three of us. Those photographs would become the lasting souvenirs of the trip.

It turned out to be the highlight of the day.

We continued searching the lake for several more hours but saw surprisingly few muskies. Eventually I got my chance.

Luke spotted another fish and positioned the boat. I made my cast and began working the lure back according to Luke’s instructions. Unfortunately, the fish showed little interest. Luke diplomatically informed me that my lure action needed improvement.

“Your twitches are too long and too quick,” he said.

He was undoubtedly correct.

The muskie remained unimpressed, and my opportunity disappeared.

Later Jesse had a chance at another fish but was similarly unsuccessful.

Luke told us that there are days when he does not catch a single muskie and exceptional days when his clients catch five or six. Considering the reputation of muskies as the fish of 10,000 casts, the fact that we landed one at all felt like a victory.

One of the pleasures of a guided fishing trip is the opportunity to talk with the guide, and Luke was an excellent storyteller.

One story involved an eleven-year-old boy who had fished with him several years earlier. The boy wanted badly to catch a muskie, but he lacked the strength and endurance needed to repeatedly cast heavy lures and retrieve them all day. Luke found himself doing much of the work.

The boy was frustrated and embarrassed.

“What do I need to do so I can do it myself next year?” he asked.

Luke told him he needed to get stronger and suggested a push-up program. Together they developed a plan and entered it into the boy’s phone. The goal was to gradually increase the number of push-ups performed each week.

The following year, when the boy returned as a twelve-year-old, he proudly told Luke that he had followed the plan and was now doing one hundred push-ups every day.

I found that pretty impressive.

Luke told another story about a young boy who wanted a pretty girlfriend. The boy asked for advice.

Luke told him, “Talk to every girl you meet, not just the prettiest one.”

He encouraged the boy to ask questions and show genuine interest in people. What classes are you taking? What do you like to do? What sports do you play?

According to Luke, if you learn how to talk comfortably with everyone, people will naturally enjoy being around you.

The boy later returned and informed Luke that his strategy had worked.

Fishing guides often spend long days talking with clients, and over time they accumulate a surprising amount of practical wisdom. Luke certainly seemed to have collected his share.

Around noon we headed back to the dock.

Once there, Luke, Jesse, and Briar helped me secure the remains of my front bumper well enough for the drive home. After thanking Luke for a memorable day on the water, we said our goodbyes and headed our separate ways.

I drove home without a muskie to add to my species list.

But Briar had caught one.

I had learned a great deal about muskie fishing, enjoyed the company of good people, survived a collision with a deer, heard some memorable stories, and spent a beautiful August morning on a Minnesota lake.

All things considered, it was a pretty good day.

Species #35: Hornyhead Chub

Today I was driving from my home in Rochester, Minnesota to Brainerd, Minnesota (about 3.5 hours to the north) where I planned to spend the night at a Holiday Inn before an early morning (6am) guided muskie trip.

As I headed north, I checked iNaturalist to see whether there might be any fish in the area that were new to my species list. From what I could tell, the Hornyhead Chub was my best opportunity.

The tributaries of the Rum River are considered good habitat for Hornyhead Chubs, particularly around Princeton and Milaca, towns about fifty miles south of Brainerd. As I approached the area, I began looking for places where I could access the river.

It proved more difficult than I expected.

I drove from one possible access point to another, growing increasingly frustrated as each location turned out to be unsuitable or inaccessible. Eventually, I came upon the Rum River Canoe Access on 320th Street and decided to give it a try.

The river was fairly wide, perhaps one-hundred feet across, but quite shallow. Just downstream from the bridge, however, I found a promising stretch with a transition from a run into a series of riffles.

I rigged a size 10 hook with a tiny piece of worm and a small split shot. The split shot was so light that casting any distance was difficult, but I managed to get the bait into the transition zone between the run and the riffles.

Almost immediately I began getting bites.

The problem was that I wasn’t hooking anything.

I suspected that even a size 10 hook might be too large for whatever was nibbling at the bait. Then I remembered that I had some tiny hooks in my tackle box, probably around size 20.

Unfortunately, several obstacles got in the way. I had misplaced my reading glasses, the evening light was fading rapidly, and my six-pound-test line seemed too thick for the tiny hook eye. After several unsuccessful attempts to thread the line, I finally abandoned the idea.

I went back to the size 10 hook and kept fishing.

Eventually I hooked and landed a small fish, only four or five inches long.

Hornyhead Chub

I took a few photographs and uploaded them to iNaturalist. The identification algorithm suggested Creek Chub as the most likely species, with Hornyhead Chub as a secondary possibility. I reluctantly selected Creek Chub. After all, Creek Chub was already on my species list, and I didn’t want to get my hopes up.

But I did.

A little later, several experienced observers reviewed the photographs and concluded that the fish was actually a Hornyhead Chub.

My wish had come true.

Moments like this are what make species hunting so enjoyable. There is the anticipation of finding something new, the uncertainty of the identification, the quiet hope that the fish will turn out to be the rarer species, and then the verdict arrives from a group of knowledgeable naturalists. Sometimes the answer disappoints. This time it didn’t.

The Hornyhead Chub became species number 35 on my list, and the Rum River earned a special place in my 100 Fish Adventure.

Fish Caught by Family (35 species)

Below is a running list of the fish I have caught, organized by family.

Acipenseridae (Sturgeon family): 1 species
Lake Sturgeon (Huso fulvescens)


Catostomidae (Sucker family): 4 species
Northern Hog Sucker (Hypentelium nigricans)
White Sucker (Catostomus commersonii)
Shorthead Redhorse (Moxostoma macrolepidotum)
Golden Redhorse (Moxostoma erythrurum

Centrarchidae (Sunfish family): 9 species
Bluegill (Lepomis macrochirus)
Green sunfish (Lepomis cyanellus)
Pumpkinseed (Lepomis gibbosus)
Rock bass (Ambloplites rupestris)
Largemouth bass (Micropterus nigricans)
Smallmouth bass (Micropterus dolomieu)
Alabama bass (Micropterus henshalli)
Black crappie (Pomoxis nigromaculatus
White crappie (Pomoxis annularis

Clupeidae: 1 species
American gizzard shad (Dorosoma cepedianum)

Esocidae (Pike family): 1 species
Northern pike (Esox lucius)

Hiodontidae (Mooneye family): 1 species
Mooneye (Hiodon tergisus)

Ictaluridae (North American freshwater catfish family): 4 species
Black bullhead (Ameiurus melas)
Yellow bullhead (Ameiurus natalis
Channel catfish (Ictalurus punctatus)
Flathead catfish (Pylodictis olivaris)

Leuciscidae (True Minnows, Shiners, Daces): 3 species
River Chub (Nocomis micropogon)
Common Shiner (Luxilus cornutus)
Hornyhead Chub (Nicomis biguttatus)

Moronidae (Temperate bass family): 3 species
White bass (Morone chrysops)
Wiper (Morone chrysops × M. saxatilis)
Yellow bass (Morone mississippiensis)

Percidae (Perch family): 2 species
Yellow Perch (Perca flavescens)
Walleye (Sander vitreus)

Salmonidae (Trout, salmon, char, etc.): 5 species
Rainbow Trout (Oncorhynchus mykiss
Brook Trout (Salvelinus fontinalis
Brown Trout (Salmo trutta)
Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii)
Salmon spp.

Sciaenidae (Drum/Croaker family): 1 species
Freshwater drum (Aplodinotus grunniens)

How Many Fish Species Are There?

I was reading the introduction to Ken Schultz’s excellent Field Guide to Freshwater Fish and was surprised to see the statement that there are approximately 21,000 fish species. That didn’t sound right. I thought I had recently read that the number exceeded 30,000.

I checked the copyright date and discovered that Schultz’s book was published in 2004, more than two decades ago. A little research revealed that the number of known fish species has increased dramatically since then. Today, there are approximately 37,700 recognized living fish species, nearly 17,000 more than the estimate cited in 2004. Fish taxonomy is one of the fastest-growing areas of vertebrate biology.

The most authoritative databases currently report:

Why has the number increased so much since 2004?

Several factors have contributed to the jump from roughly 21,000 to nearly 38,000 species:

  • A huge increase in taxonomic research, with hundreds of new species described annually. (For example, 409 new species were described in 2025 and another 217 by mid-2026.)
  • Exploration of previously inaccessible habitats, including deep-sea environments, remote Amazon tributaries, and isolated Indonesian islands.
  • Advances in genetic analysis, which have revealed that many “single” species actually consist of multiple distinct species.
  • Improved global databases that have standardized names, resolved synonyms, and corrected misidentifications.
  • Increased funding and research focused on highly diverse groups such as catfish, minnows, carps, loaches, and reef fishes.

What I find particularly remarkable is that although freshwater accounts for only about 0.01% of Earth’s water, it contains roughly 15,000 fish species, or about 40% of all fish diversity.

Why are freshwater habitats so species-rich?

Freshwater environments are naturally fragmented into rivers, lakes, springs, caves, and isolated drainage systems. These barriers separate populations and promote speciation over time. One of the most diverse freshwater groups, the Cypriniformes (carps, minnows, and loaches), alone contains roughly 4,500 species.

This raises another question: Why are fish so much more diverse than other vertebrate groups such as birds and mammals?

Several evolutionary and ecological factors contribute:

Time. Fish have been around for more than 500 million years, giving them far longer to diversify than mammals or birds.

Geographic isolation. Freshwater systems continually isolate populations, accelerating speciation.

Habitat diversity. Marine environments provide an extraordinary array of ecological niches, including coral reefs, open oceans, deep-sea trenches, kelp forests, estuaries, and polar seas.

Genomic innovation. Teleost fishes underwent an ancient whole-genome duplication event, creating extra genetic material that could evolve new functions.

Ecological breadth. Fish occupy an astonishing variety of habitats, including:

  • caves
  • coral reefs
  • rivers
  • lakes
  • swamps
  • open oceans
  • deep-sea trenches
  • polar waters
  • desert springs

No other vertebrate group occupies such a diverse range of environments.

Morphological flexibility. Fish have evolved an extraordinary variety of adaptations, including:

  • electric organs
  • venom glands
  • suction discs
  • bioluminescent lures
  • transparent bodies
  • highly specialized jaws
  • unusual reproductive systems

This evolutionary flexibility has helped drive diversification across hundreds of millions of years.

Even with approximately 37,700 described species, ichthyologists estimate that 10,000 to 20,000 fish species remain undiscovered, particularly in Amazon tributaries, the Congo Basin, Indonesian archipelagos, deep-sea habitats, and isolated karst spring systems.

If those estimates prove correct, the eventual number of recognized fish species could exceed 50,000, making fishes by far the most diverse group of vertebrates on Earth.



Minnow-sized Fish List (12 species)

While my goal is to catch 100 species of fish, I have also developed an appreciation for the smaller species that often go unnoticed. Many anglers dismiss minnows, darters, and other small stream fishes, but I find them fascinating. They come in a surprising variety of shapes, colors, and habitats, and learning to identify them has added a new dimension to my time on the water.

The fish on this page are not included in my 100-species challenge unless I have also caught them by hook and line. So far, that includes the Creek Chub, Common Shiner, and White Sucker. The species listed here represent a running list of the minnow-sized fishes I have collected, identified, photographed when possible, and released. All were caught using a dip net or minnow net while exploring streams, rivers, and lakes.

Every small creek, river, and lake seems to hold its own collection of these overlooked species. I suspect this list will continue to grow as I explore new waters and learn more about the remarkable fishes that live beneath the surface.

Species Caught
Bigmouth Shiner (Ericymba dorsalis)
Central Stoneroller (Campostoma anomalum)
Common Shiner (Luxilus cornutus)
Creek Chub (Semotilus atromaculatus)
Emerald Shiner (Notropis atherinoides)
Fathead Minnow (Pimephales promelas
Iowa Darter (Etheostoma exile)
Johnny Darter (Etheostoma nigrum)
Northern Hogsucker (Hypentelium nigricans)
Rainbow Darter (Etheostoma caeruleum)
Spotfin Shiner (Cyprinella spiloptera)
White Sucker (Catostomus commersonii)

Current total: 12 species

Species #34: Mooneye

I wasn’t expecting today’s fishing trip to produce a new species for my list. To my surprise, I ended up catching not one but three Mooneyes from two different spots on the Zumbro River.

The first two came from a stretch of the river near the small town of Theilman, Minnesota. The third was caught about 10 miles downstream near Kruger campground.

At both locations I was fishing a small red worm on a size 8 hook with a sinker about a foot above it. I started with a 1/4-ounce sinker and later switched to a 1/2-ounce sinker.

Catching these fish was interesting. I would get fairly firm bites, but then there would be little resistance for a few seconds. When I finally decided to check whether I actually had a fish on the line, I discovered that I did. They didn’t fight much at first, but as they neared shore they came alive and put up a surprisingly strong battle.

I was excited when I first saw one because it was bright silver and a decent size and quite beautiful zagging back and forth in the clear water. While reeling it in, I imagined it might be a Silver Redhorse, a species I still need for my list. Once I landed it, I briefly wondered whether it might be a White Bass. The large bulging eye, however, immediately caught my attention and seemed very different from the eye of a White Bass.

Mooneye

I uploaded a photo to iNaturalist and was delighted when it identified the fish as a Mooneye.

The fish were also larger than I expected. For some reason, I had always imagined Mooneyes as relatively small fish, perhaps even smaller than Bluegills. Instead, the three I caught were all around 10 to 12 inches long. I caught the first two in a deep pool just beyond a seam in the river.

My afternoon of fishing was accompanied by somewhat amusing, but also somewhat annoying, bellowing cows. They were standing in the river about fifty yards upstream from where I was fishing and seemed determined to make their presence known.

Near the end of my time at Theilman, a couple of canoeists pulled out while I was fishing. One asked whether I had caught anything.

“A couple of fish,” I replied.

“What kind?”

“I think they’re Mooneyes.”

He looked puzzled.

“You know what those are, right?” I asked.

“Some kind of sucker?”

I was pretty sure they weren’t (I double checked and they aren’t) but I simply agreed to spare him any embarrassment and bring the conversation to a graceful conclusion. He then told me he had caught a couple of Smallmouth Bass on a jig while floating down the river.

I enjoy catching Smallmouth as much as anyone, but sometimes it seems as though everyone is chasing the same handful of popular sport fish when there is such remarkable diversity swimming beneath the surface. Discovering unfamiliar species is one of the things I enjoy most about fishing.

The Mooneye (Hiodon tergisus) is a primitive North American freshwater fish known for its large, silvery, reflective eyes, which give it both its appearance and its common name. It belongs to the family Hiodontidae, one of the oldest surviving lineages of ray-finned fishes in North America.

Mooneyes are widely distributed across eastern and central North America, including the Mississippi River drainage and the Great Lakes region. Minnesota lies right in the middle of their range.

They can reach nearly 19 inches in length, although fish in the 10 to 12 inch range are more typical, which was approximately the size of the three I caught. I was genuinely surprised by their size because I had somehow formed the impression that mooneyes were much smaller fish.

Mooneyes prefer rivers, lakes, and ponds and are often associated with relatively clear water, which fit the conditions on the Zumbro that day. They are slender, bright silver fish with very large eyes, a deeply forked tail, a single dorsal fin, and a body shape somewhat reminiscent of a herring or shad.

The eyes contain a reflective layer that helps them see in low-light conditions, making them particularly active at dawn, dusk, and during the night. They are opportunistic predators that feed on aquatic insects, other invertebrates, and small fish. As mentioned above, mine apparently had no objection to adding small red worms to their menu. They often feed near the surface and may sometimes be seen chasing insect hatches.

The Mooneye’s closest living relative is the Goldeye (Hiodon alosoides). Both belong to the genus Hiodon. Goldeyes generally prefer murkier water and are distinguished by their golden-colored irises.

Although Mooneyes are rarely targeted by anglers, they are strong fighters on light tackle and are frequently caught incidentally by fishermen pursuing Bass, Walleye, or Trout. They also play an important role as forage fish in many river ecosystems.

From an evolutionary standpoint, mooneyes are particularly fascinating. They are sometimes described as living fossils because their lineage stretches back at least 50 million years to the Eocene Epoch. Fossils of related species have been found across western North America, providing a glimpse into a remarkably ancient branch of the fish family tree.

State Fish

Here is a list of official state fish by state. Quite a few states share the same fish. For example, nine states have selected the Brook Trout as their state fish. In contrast, 28 states have chosen a fish that no other state claims. Hawaii’s state fish, the Humuhumunukunukuāpuaʻa (Reef Triggerfish), is one such example and, not surprisingly, is unique. A few states have designated separate freshwater and saltwater state fish and three states (Iowa, Indiana, and Ohio) do not have a state fish.

StateOfficial State Fish
AlabamaLargemouth Bass; Tarpon (saltwater)
AlaskaKing (Chinook) Salmon
ArizonaApache Trout
ArkansasAlligator Gar
CaliforniaGolden Trout; Garibaldi (saltwater)
ColoradoGreenback Cutthroat Trout
ConnecticutAmerican Shad
DelawareWeakfish
FloridaFlorida Largemouth Bass; Atlantic Sailfish
GeorgiaLargemouth Bass; Southern Appalachian Brook Trout; Red Drum
HawaiiHumuhumunukunukuāpuaʻa (Reef Triggerfish)
IdahoCutthroat Trout
IllinoisBluegill
IndianaNone
IowaNone
KansasChannel Catfish
KentuckyKentucky Spotted Bass
LouisianaWhite Crappie; Spotted Seatrout
MaineLandlocked Atlantic Salmon
MarylandStriped Bass (Rockfish)
MassachusettsCod
MichiganBrook Trout
MinnesotaWalleye
MississippiLargemouth Bass
MissouriChannel Catfish
MontanaWestslope Cutthroat Trout
NebraskaChannel Catfish
NevadaLahontan Cutthroat Trout
New HampshireBrook Trout; Striped Bass
New JerseyBrook Trout; Striped Bass
New MexicoRio Grande Cutthroat Trout
New YorkBrook Trout; Striped Bass
North CarolinaSouthern Appalachian Brook Trout; Red Drum (Channel Bass)
North DakotaNorthern Pike
OhioNone
OklahomaWhite Bass
OregonChinook Salmon
PennsylvaniaBrook Trout
Rhode IslandStriped Bass
South CarolinaStriped Bass
South DakotaWalleye
TennesseeSmallmouth Bass
TexasGuadalupe Bass
UtahBonneville Cutthroat Trout
VermontBrook Trout
VirginiaBrook Trout; Striped Bass
WashingtonSteelhead Trout
West VirginiaBrook Trout
WisconsinMuskellunge (Muskie)
WyomingCutthroat Trout

Species #33: Walleye

Yesterday I went fishing with my son-in-law Luke. We started at a spot along the Zumbro River in Rochester, but after a while neither of us had gotten a bite. I told him I knew a place farther upstream where I had always caught plenty of fish: the tailwaters below the Silver Lake Dam.

The move paid off. We immediately began catching fish, mostly Bluegills and Black Bullheads, although Luke also landed a couple of Smallmouth Bass and a Yellow Perch.

I spent most of the morning fishing my usual bottom rig: a size 6, 8, or 10 hook baited with a red worm, with a small bank sinker (about 1/8 ounce) positioned roughly 12 inches above the hook. The fishing was good, but after a while I decided it would be fun to try something different.

I removed the small hook and tied on a large 1/0 circle hook. Instead of using a piece of worm, I threaded on an entire worm. I told Luke that the change probably didn’t make much sense, but I was going to give it a try anyway.

It wasn’t long after I cast it out that I felt a solid bite. This fish fought much harder than the others. As I reeled it in, I told Luke, “I think it’s a Redhorse.”

“No,” he replied. “That’s not a Redhorse. That’s a Walleye!”

Walleye

I was completely surprised. A Walleye was the last fish I expected to catch at that location. I had assumed I would need to fish a northern Minnesota lake or perhaps the Mississippi River before eventually adding one to my 100-species list. So, instead of traveling to a northern Minnesota lake or the Mississippi River, I caught Species #33 right here in Rochester.

I then asked Luke to take a picture of me with the fish but every time Luke got ready to snap a photo, the fish wriggled out of my hands and onto the bank. Luke was laughing hard and after each escape attempt he would say, “Kevin! Hold on to the fish!” Eventually we managed to get a photo.

With this Walleye, I am now one-third of a fish away from being one-third of the way to my goal of 100 fish species. Only a serious fish nerd would think that milestone is worth celebrating, but I do!

Minnow Day

I have been wanting to learn more about minnow-sized fish ever since I started my goal of catching 100 fish species this year.

I should clarify that when I say “minnow-sized,” I am referring to small fish, typically 2-4 inches long, and not necessarily members of the Minnow family. Most species in the minnow family are indeed small, but there are notable exceptions, such as the Common Carp, which can grow to enormous sizes. I do not plan to count minnow-sized fish on my 100-species list, but I am nonetheless very interested in learning more about them.

My son-in-law, daughter, and my grandchildren joined me for an outing to the Zumbro River just south of Apache Mall in Rochester, Minnesota. My daughter, who has become an excellent watercolor painter, took a well-deserved break and spent her time under a shady tree painting a beautiful hummingbird. Meanwhile, the rest of us went hunting for minnows.

At first, my son-in-law and I tried using a seine net in the moderately fast-flowing current of the river. We caught exactly zero minnows with that method and eventually gave up. We then noticed that there were large numbers of minnows in the shallow, slow-moving rivulets along the edge of the river.

Fortunately, I had also brought a dip net. My son-in-law, who is quite a bit faster than I am, quickly began catching minnows and placing them in a bucket. We photographed each fish and then asked iNaturalist to help identify it.

Among the approximately 50 minnow-sized fish we caught were seven different species:

Johnny Darter
Bigmouth Shiner
Rainbow Darter
Central Stoneroller
Creek Chub
Northern Hog Sucker
White Sucker

The first four species remain minnow-sized throughout their lives. The last three were juvenile fish that will eventually grow much larger. Adult Creek Chubs typically reach 4-8 inches in length, White Suckers commonly grow to 12-18 inches, and Northern Hogsuckers often reach 10-18 inches.

One thing I learned while researching these fish is that minnow-sized species generally live much shorter lives than larger fish. Shiners, dace, darters, and killifish often live only two to four years, whereas larger species such as suckers, sunfish, bass, and catfish commonly live eight to twenty years or more.

There are several reasons for this difference. First, small fish experience intense predation pressure. They are preyed upon by bass, pike, walleye, herons, turtles, and even larger fish. Second, their high metabolic rates cause them to burn energy quickly and generally age faster. Third, many small species follow a “live fast, reproduce fast” strategy, spawning multiple times each year and producing large numbers of offspring. Finally, the shallow creeks, riffles, and stream margins where many small fish live are often unstable environments that can be affected by floods, droughts, heat waves, and winter freezing.

Fortunately for these species, their short lifespans are offset by rapid reproduction, allowing populations to rebound quickly after environmental setbacks.

We had a very enjoyable afternoon catching fish and learning more about a fascinating group of species that most anglers rarely pay much attention to. Although none of these fish will count toward my 100-species goal, they reminded me that some of the most interesting discoveries in nature come in very small packages.

What Do Fish Eat? A Beginner’s Guide to Fish Diets

If you were to ask me just several days ago what various fish eat, I would have been pretty clueless. I knew that many fish eat worms, and some eat minnows and leeches, because you can buy all of those as fishing bait and because I have caught a wide variety of fish with worms over the years.

But I figured that was probably a pretty uneducated understanding of what fish eat, so I looked into it more. It turns out that the diets of fish can be classified into about eight categories: planktivores, piscivores, insectivores, benthivores, molluscivores, detritivores, algivores, and omnivores.

Before I explain what each of those is, it is helpful to know that -vore is Latin for “one who devours.” More precisely, it comes from the Latin verb vorāre, meaning “to devour,” “to swallow greedily,” or “to eat ravenously.”

Planktivores are microscopic grazers that feed on zooplankton—for example, tiny drifting animals such as Daphnia, copepods, and rotifers. Examples include juvenile Perch, juvenile Trout, Cisco, Shad, Killifish, and many Minnows. Planktivores are usually small-bodied or juvenile fish. They occupy open water and often form schools. They are the crucial link between microscopic life and larger predators. Almost every fish begins life as a planktivore. Even Pike and Bass start out eating zooplankton before graduating to bigger prey.

Omni- of course means “all,” and consequently omnivorous fish are generalists that eat a mix of plants, insects, small crustaceans, detritus, and sometimes tiny fish. Examples include Bluegill, Carp, Creek Chub, and many Minnows. These fish are adaptable and thrive in ponds, lakes, rivers, and marshes. Their flexibility is why Bluegills dominate many warm-water lakes and why Carp can survive almost anywhere.

Piscivores eat other fish. They are the apex predators of freshwater systems. Examples include Northern Pike, Muskie, Largemouth Bass, Walleye, Flathead Catfish, Bowfin, and Gar. Piscivores shape fish communities. They control panfish numbers, influence prey behavior, and often determine where other species can safely feed. Their bodies reflect their diets: long jaws, sharp teeth, fast-twitch muscles, and ambush-oriented shapes.

Insectivores feed on aquatic insects such as mayflies, caddisflies, midges, stoneflies, and larvae. Examples include Trout, Darters, many Minnows, and juvenile Bass. These fish rely on clean, oxygen-rich water. Their presence often indicates a healthy stream or lake. Trout are the classic insectivores: they rise to drifting insects, pick larvae off rocks, and track hatches with precision.

Benthivores feed on organisms living on or in the bottom sediments. Examples include suckers, catfish, sturgeon, and sculpins. They eat insect larvae, worms, small crustaceans, and detritus. Their mouths are often downturned, adapted for rooting through or vacuuming the substrate. This category includes many of the species I have spent a lot of time fishing for with bottom rigs—especially suckers, which are classic benthic specialists.

Molluscivores, also known as the “shell crushers,” are fish that specialize in eating snails, clams, and mussels. Examples include Redear Sunfish (the “shellcracker”) and Freshwater Drum. They have strong pharyngeal teeth designed to crush shells. This diet helps control invasive snails and can influence water clarity.

And finally, detritivores and algivores are considered the clean-up crew because they eat algae or decomposing organic matter. Examples include certain Minnows, some Suckers, and various tropical species. They recycle nutrients and help stabilize ecosystems.

It is important to realize that fish diets change as they grow. A single species may pass through multiple feeding categories:

  • Bluegill: planktivore → insectivore → omnivore
  • Perch: planktivore → insectivore → piscivore
  • Trout: planktivore → insectivore → occasional piscivore
  • Bass: planktivore → insectivore → piscivore

Understanding these transitions explains why fish occupy different habitats at different life stages. Knowing feeding strategies helps predict where fish hold, what bait works, when they feed, how species interact, and why certain lakes produce particular fish communities.

In other words, the next time I put a worm on a hook, I will have a much better idea of what might be interested in eating it.