First off, I am not aware of suppliers of organic catfish feed (which doesn't mean they don't exist). I suspect the scarcity of organic pet food tells a similar tale for somewhat similar products such as fish feed. One impediment to the availability of organic catfish food might be the current dearth of certified organic fish production. If the 2001 information at this link
http://www1.agric.gov.ab.ca/$department ... enDocument
is accurate, both situations may be changing or have the impetus to change some before very long. As the Suzuki article I posted under the Salmon topic in the Food forum suggests, a major source of contamination is the bio-accumulated toxics in the fish meal portion of common fish feed. At least one maker:
produces fish meal-free fish feeds. There may be other manufacturers. I'm not sure how easy it would be to home-make catfish feed because I'm not sure of what form, particle size, and firmness is needed. If you can find a source for "certified" organic farm-raised fish, you probably can find out who makes the feed for them. On the other hand, maybe someone who actually knows something about it can give you a more direct answer.