If you put the bloodworms in after the lights are out, there's more chance of the kuhlis getting them. Tetras are pretty heavy sleepers, and tend to go to sleep as soon as the lights are out. Kuhlis stay awake at night, and will go searching for food.
I think the kuhlis would also enjoy frozen brine shrimp, but you don't have to get both brine shrimp and bloodworms, one or the other is fine.