Just wondering why the Sterbi Cory has that white on him i dont think its a fungus also in my other tank i got plants and i noticed in a fry tank little black hoppers you would never catch them are they harmless or can i get rid of them thanks
The cream patch on top of the catfish's head is probably excess mucous. As long as the fish isn't rubbing on anything and none have died, and the water is clean (0ppm ammonia, 0ppm nitrite, less than 20ppm nitrate), they should be fine.
No idea about the black things. I really can't tell anything from the pictures.