I've fished for catfish in just about every type of water you can think of ... stagnated water, clear water, murky water, and muddy water, and you have to adjust to the water types you're fishing.
Fishing in stagnant water is good for catfish, bullhead, and a few other species of fish but if you fish here be aware that the fish might not taste very good mainly due to the water. These types of waters can be sleus or even ponds can be stagnant due to several reasons like nearby sewage treatment facility or something like that or even sewage running off into the pond's tributary/creek that's feeding the pond. This type place is a great place to catch catfish for sport as the pond will most likely be overstocked or have very large amounts of catfish due to little or no fishing pressure. The reason I'd fish in this type water is just for sport ... a lot of times the action is very fast and most of the time they'll bite on anything you throw at them if it's natural.
Real muddy water is the same like the Deep Fork river that originates right through the middle of OKC, OK and runs east through my old stomping ground around Davenport OK and Sparks OK. You fish around any good hole that has structure like log jams or something like that and you can catch a lot of catfish ... the fish out of Deep Fork are pretty decent tasting as well.
Clear water where the fish are really healthy and have an abundant food supply you will have to fish fresh bait in most cases and nothing they don't feed on naturally .... they can't go to the store and buy "Fester's Catfish GoGo-Getter" or some other stuff you'd buy at the store ... these fish will be a challenge to figure out but once you do you can catch a lot of them ... I'm not talkin about two a day or 4 or so. I'm talkin bout 12 to 15 per day easily. CATFISH FEED CONSTANTLY... I'm not saying they don't quit biting ever but I am saying they follow patterns and they are all thinking alike just like they're joined mentally ... you could be fishing and catching several fish and all of a sudden they quit like you just caught the last one ... there are two or three reasons this happens. First one is catfish school and migrate through areas feeding and they're usually holding pretty tight together within like 5 ft of one another and the school usually consists of anywhere from 5 to 50 or even more depending on the size of the empoundment you're fishing. Once the fish move through and pass on from where you're fishing you'll need to relocate or figure out where or which way they were going. They do this quite a bit in Keystone Lake ... you can be fishing catching several nice blues and then all of a sudden they're gone .... all you have to do is get back into their path ... most of the time the best bet is follow the current ... if the water level is dropping I move down stream about 100 yds ... if it's rising I'll move upstream ... I don't always catch them coming through again but sometimes I get lucky and catch three or so more fish. Fish finders are really handy in relocating the fish in this instance ... If you're fishing a smaller body of water this probably wouldn't be the case ... they may need another bait presented to them ... in a lot of cases that'll make them start biting again. If the water level drops abruptly like it does behind dams when they shut down a turbine that's generating electricity it's just like if they was feeding in flooded creeks or channels ... when the water level drops they have a natural instinct to move to deeper water ... it's hard for them to find any deeper water behind dams but none the less it will make the fish move or relocate to a different spot. This is all just general info and what I'm trying to get accross is there's a lot of variables to contend with when fishing for catfish ... you'll develope an instinct for catching them if you stay at it long enough and soak up enough of what mother nature's little creatures are telling you. Be very observant and pay attention to everything and theorize to yourself what's going on at all times even when you're catching fish there's something to learn.