Catfish of the Month Right Arrow September 2008 • Article © Bill Hoppe, uploaded September 01, 2008



Slender Madtom, Slank Giftmalle (Denmark) - Noturus exilis   Nelson, 1876

Bill Hoppe provides this months insight into collecting and maintaining this small North American native catfish.

This article is based on my experiences, over the last year, of collecting and maintaining Notorus exilis. Although I have not yet spawned this species, I intend to try to initiate both a tank and pond spawning in the coming year.

I had wanted to collect some madtoms after I started collecting U.S. native species last year, but thought it might be a little more than a novice collector could hope for. Especially when someone told me they should be collected at night. Stumbling around in a strange creek in the dark on my own was not a high-ranking entry on my wish list. The one time I tried some evening collecting I found myself surrounded by 3 water snakes. It crossed my mind that among these might be one or more poisonous cottonmouths. Needless to say, I made quite a wake getting out of there. Looking back, two of the snakes had followed me to the bank and their heads were visible from the shore. They were not nervous at all; I was, however, a trembling wreck.

One spring day while out collecting darters in a local creek with a dip and kick nets, I caught site of a dashing squiggle on the bottom of the creek. Now that I was alert, I spotted two more dashing from rock pile to rock pile. I was thinking these had to be madtoms, but I had never seen a live one. The next time a squiggle showed itself I made a wild stab and there in my net was a nice healthy looking madtom. I saw two more make a dash for a pile of rocks in a slightly deeper area of the creek but was too late to catch them with the net.

I moved to the pile of rocks, put my net downstream of the pile, and kicked up some dirt upstream of the pile to cloud the water to make the net less visible. I then kicked over the pile of rocks and collected two more madtoms and called it a day. I discovered that these madtoms could be active late in the afternoon and found this the same in an aquarium.

These "early birds" will show up 2 or 3 hours before sunset. If I have to wade with poisonous snakes, I would rather not do it in the dark. Later, I collected slender madtoms in minnow traps set overnight. I even collected a water snake in a minnow trap as well. The snake enters looking for fish to eat and then can not get back out and drowns. My apologies to snake lovers everywhere.

During their first two days in captivity, the madtoms did not seem to eat anything. Once they did start eating there was no problem feeding them at all. They just seemed to need a day or two to adjust. I put several madtoms in an outdoor tank with a light on it at night. We have few mosquitoes here, but the moths would come to the light, hit the water and disappear in a swirl as the madtoms patrolling the surface gulped them down. Wings were often broken off and floated back to the surface where I removed them in the morning. In studies, wild specimens consumed insects such as midge flies, caddisflies, and some filamentous algae. In an aquarium, they are quick to respond to the introduction of food. They enjoy bits of liver and shrimp. Brine shrimp are taken very quickly as well as just about any prepared aquarium foods.

N. exilis like shallow creek riffles with rocky bottoms, normally, 6 to 12 inches deep but during the heat of summer here in Arkansas I have collected them in 3 to 4 feet deep pools. Those I have collected here have more intense dark markings than I have seen in most photographs of slender madtoms.

Slender madtoms do not seem to be aggressive as young bullheads. I have seen no indication of my madtoms bothering tank mates. Though nocturnal, they can be coaxed out for a showing by introducing an especially enticing treat to the tank. They prefer cool temperatures but seem to adapt to low 80°F too.

Altogether, slender madtoms are an ideal aquarium fish. Just do not try to cuddle with those poison spines! The little fellows demand respect. An especially endearing fact is their tendency to spawn in beer cans. Place one can for each male for use as caves if you want that "natural" look. If you are abstaining from beer try building assorted sizes of rock caves and overhangs. Try a ratio of two males to each female. I believe that the female spawns half her eggs with one male and then goes looking for another. At spawning time the male has a swollen head and the female has a noticeably swollen belly.


Copyright information for the images used in this article can be found on the species' full Cat-eLog page.

Jump to next section Cat-eLog Data Sheet
Scientific NameNoturus exilis  Nelson, 1876
Common NamesSlender Madtom
Slank Giftmalle (Denmark)
Type LocalityMackinaw Creek, Illinois R. drainage, McLean Co., Illinois., U.S.A.
Pronunciationno two russ
EtymologyFrom the Greek notos, meaning back and oura, meaning tail. In reference to the confluent adipose and caudal fins. The specific epithet is in reference to the slimness of the specimen's body.
Jump to next section Species Information
Size 150mm or 5.9" SL. Find near, nearer or same sized spp.
IdentificationLong slender body;flat head. Black border on median fins. Terminal mouth with equal jaws. Yellow-brown to gray-black above;light yellow below; pale or light yellow fins.
SexingBreeding male with swollen lips,enlarged cephalic epaxial muscles, and large bulbous genital papilla. Female with papilla with deep median groove ending in a small bump.
General RemarksOccurs in clear, cool, rocky riffles, runs and flowing pools of creeks.
Jump to next section Habitat Information
DistributionNorth America: Green, Cumberland and Tennessee River drainages in central Kentucky to northern Alabama, USA; upper Mississippi River basin from southern Wisconsin and southern Minnesota to Ozark and Ouachita Highlands of Arkansas, Kansas and Oklahoma in USA.
Gulf Coast Drainages, Mississippi, Ohio, Green River (Kentucky) (click on these areas to find other species found there)
Gulf Coast Drainages, Mississippi, Ohio, Cumberland (click on these areas to find other species found there)
Gulf Coast Drainages, Mississippi, Ohio, Tennessee (click on these areas to find other species found there)
Gulf Coast Drainages, Mississippi, Upper Mississippi (click on these areas to find other species found there)
Show it on a map (Click the map-icon to show/hide map of species distribution)
IUCN Red List StatusLeast Concern
pH6.2 - 7.0
Temperature14.0-22.0°C or 57.2-71.6°F (Show species within this range)
Other ParametersHighly oxeganated water a must.
Jump to next section Husbandry Information
FeedingReadily feeds on live and frozen foods. Will also adapt to flake and prepared foods for the aquarium.
FurnitureProvide sand mixed with peat moss,pvc pipes,flat rocks and vegetation .
CompatibilitySuitable for a coldwater community tank.Ideal tank mates include small-midsized North American native fishes such as darters and shiners.
Suggested TankmatesIdeal tankmates include small to midsized North American native fishes such as darters and shiners.
BreedingSpawning occurs in the months of may-august. It is difficult in the aquarium however it has been done when wild caught specimens are added to aquariums with warmer temperatures than the river or drainage system they are captured from.
Jump to next section Further Information
ReferencesBull. Illinois Mus. Nat. Hist.v. 1 (no. 1) - pp51
A Field Guide To Freshwater Fishes North America
North American Native Fishes for the Home Aquarium
American Aquarium Fishes
Registered Keepers(1) Silurus, (2) mikey (k: 12), who also notes: "Hardy little fish captured in Big Sugar Creek near Pineville, MO", (3) irshprncsk.

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Breeding ReportsNone.
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Last Update2007 Apr 30 09:24 (species record created: 2008 Sep 01 11:22)

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