Slender Madtom, Slank Giftmalle (Denmark) - Noturus exilis Nelson, 1876
Article © Bill Hoppe, uploaded September 01, 2008.
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 pondspawning 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 crossedmy 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.
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