In Minnesota we are kind of limited on the types of fish we can use for catfishing bait. It is illegal to use whole or parts of game fish (this rules out using sunfish, perch, or any other panfish), goldfish, or carp for bait. We can use bullheads as long as they are less than 7 inches in length. As long as they are under 7 inches they are considered minnows and as such we can harvest and transport them as bait. Lucky for us, bullheads are excellent flathead bait. Since the spring of 2005 I have been running a 100 gallon stock tank in which I maintain about 75 to 100 bullheads at any given time. The bait tank is equipped with a large 110 gallon aquarium power filter to treat the water and remove harmful waste and I also run a 110 volt aerator for two 10 inch airstones. I keep my bait tank in a small shed in my boat carport. This keeps it out of the weather and I am able to lock it up. I am a little paranoid that one of the grandkids may fall in it and get hurt. This also keeps the critters from trying to steal my bullheads. The aquarium power filter is an AquaClear 110 Power Filter. It mounts right on the side of the stock tank, is easy to reach to clean and operate and is relatively noise free. I run the power filter 24/7 from April to early October. I am still using my original power filter so this will be its 4th season this spring. To be honest with you it is a simple setup and operation. It has 3 filters a mechanical sponge type filter; a carbon filter; and a bacterial filter. The first couple years I ran the system I changed out the filters about once a month but last year I only changed the sponge filter one time late in the season and I ran the rest of the filters the entire season. I would rinse them out about once a month when I was doing a water change but that was it and my water was just fine the entire season and the bullheads were healthy and active. I do at least a 50% water change about every 3 to 4 days. I have my tank set up so that I can do a water change very easily in about 20 minutes. I have a sump pump in the bottom of the tank attached to a hose that runs to my driveway. I simply plug in the pump, draw down the water 50% to 75% and throw my backyard hose into the tank and refill it. While it is draining and refilling I clean the filters and I add chemicals to condition the water. I have city water and I need to treat the chemicals in the water which would be harmful to the bullheads. The water conditioner I use is called "AmQuel Plus+" and you can find it a PetCo or PetSmart. I add about an ounce to 1 ½ ounces each time I change the water. One thing I learned the hard way is to not add my bullheads to my bait tank for at least 36 hours after I catch them. One of the first times I stocked the tank I went out and caught a dozen nice 6 1/2 to 7 inch bullheads and dumped them in my tank. The next morning when I checked my tank they had crapped and regurgitated an incredible amount of slime and crud into my tank. It totally plugged my power filter and I had to take it out and clean it and all the filters completely. I ended up draining the tank and refilling it to get all the crud out. Now I keep the bullheads in a separate tank (a 32 gallon trash can) for at least 36 hours until they are crapped out. I have had no problems since I started doing this. I dont feed my bullheads because that just gets them to crapping up the tank. They can go a long time without eating but I usually purge my tank completely about every 5 to 6 weeks. When I see the numbers of bullheads getting low in the tank I will take that opportunity to empty it and completely restock. Later in the summer when water starts to heat up (75 degrees and higher) the bullheads will start to get what we call the grey crud. They get some kind of mold and start to die off, I will start to lose about 3 to 4 bullheads a day to this mold. That is a good time to restock the tank but it seems that every year about the middle of August the bullheads start to get the Grey Crud even the new ones you just restock. I dont think the crud comes from the tank, I think they pick it up from their home waters and just pass it around once they get sick. I have had little to no problems maintaining a stock of bullheads. They are a tough fish that is well suited to backyard bait tanks. They are easy to catch and transport. I have several good bullhead ponds close to my home and I dont have any trouble catching bullheads to restock the tank. I primarily maintain bullheads in my tank Ive tried suckers but they are too expensive and they die too easy. I can usually maintain suckers early in the spring when the water is cool and later in the fall again when the water is cool. I usually get a lot of questions about how much everything costs and where do you get the equipment. Here is a breakdown of what I use and the approximate costs: 100 Gallon Stock Tank Fleet Farm about $70 AquaClear 110 Aquarium Power Filter Pet Smart price varies from about $40 to $80 ask them to do a price match from the on-line Pet Smart price and you will get it for around $40 otherwise the store price is about $80. Double outlet Aquarium air pump - WalMart - about $10 Two 10 airstones and airline WalMart about $10 Optional Tank Sump Pump for water changes Menards about $40 I keep my bait tank in one of those Rubbermaid storage sheds to keep it covered and clean and to keep one of the grandkids from falling into it. You dont have to do that but the aquarium power filter is not designed for outdoor use so some type of bait tank cover may be needed. I hope you find this information useful.