NANFA-- fish behavior at dams, trip report,
Thu, 3 May 2001 12:02:08 EDT

On the trip back from turkey hunting May 1, I stopped at a small river in
central Indiana to see what I could see. I had visited the site once about a
year ago when I found crayfish with a bluish tint to them. There is a small
dam completely across the river. From the top of the dam to water level
below is about six feet. There was water going over but probably less than
normal due to record dry conditions since the first of the year.

The first thing noticed was the tremendous number, diversity and sizes of
fish gathered below the dam: several turtles, catfish, bass, sunfish,
minnows and unidentified fish that kept trying to leap up over the dam, often
getting about three feet up. None were observed making it. My hunting buddy
and I decided to drive to his house about 30 miles away and grab fishing

We got back to the site about 90 minutes later and observed the catfish and
the turtles were gone. Using bee moth larvae on a small hook, I immediately
started catching the fish trying to make it up the dam. I had never seen the
fish before: many of them were pinkish colored similar to trout, which I am
guessing is a temporary breeding color. Checking "Peterson's Guide to
Freshwater Fish," it appears they were male Creek Chubs (Semotilus
atromaculatus). All the ones I caught were about 8" long. There were
literally hundreds of them all about the same size. No females were

There were also schools of Rock Bass (Ambloplites rupestris) also about 8"
long. I caught almost 25 fish in about an hour, including a 12" bass which
was extremely dark colored. It was certainly a record for me. Everything
was released as I didn't think I could get it home without killing since I
was without my normal transporting equipment. I hope to go back in a few
days with nets and traps.

There were lots of ~1" minnows swimming in with the much larger fish as
well as the large catfish that could have easily taken the Creek Chubs.
Under what circumstance do prey and predator to swim this close together?
Could there have been an insect hatch of some sort that was washing over the
dam that they were eating? I know little of migrating behavior of freshwater
fish. Is this typical for Creek Chubs and perhaps the other fish to try and
get over the dam and migrate up stream? Or is this generally true of most
fish in the spring?

Chuck Church
Indianapolis, Indiana USA

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