Cottonseed meal is the byproduct of ginned cotton, seeds crushed and the oil extracted. It can then be used as animal feed or in organic fertilizer. I found out that catfish liked it too.
I would buy the 50 pound bags, that came in burlap sacks, for this purpose. I took the bags up to Lake Lanier and would sink them in 15-25 feet of water, tying a cement block to them to make sure they stayed in place. I found out the hard way that you can’t let the bags get wet in the process of getting them to the drop point or the smell will be overwhelming. People on the web agree, describing it as the smell of death. Obviously the reason catfish are attracted.
I would usually come back in the next few days and fish the area catching small channel cats but never the big ones I was looking for.
The carp also liked the meal and I caught several in the 5-6 pound range doing this. They are a lot of fun to reel in so it made the effort worth it in my opinion. I’m sure if you kept at it, changing locations, you would eventually catch some nice catfish too. If you had a dock, it would be simple to drop one right off the end occasionally.