Catfish is oily, of course not like salmon but it's oily. When I kept poly's I would feed catfish to help with digestion and to help prevent bloat once a week.catfish is oily? Uhm, catfish is classed as a delicate - a white meat, along w/ others like bass, cod, hake, burbot to name a few....... oily darks would be more like tuna, swordfish, bluefish, salmon etc. Your medium textures are fish like trout, bluegill, carp, and basically anthing that doesn't fit under a white or a dark, but somewhere in between