It depends how big your Koi is and how big the Catfish is. If the catfish can fit in the Koi's mouth than it will get eaten.
no if you are trying to catch catfish use clams. worms might work and big catfish will bite anchovies
12 in
The catfish that live in the pacific northwest get fairly big. The average size of these catfish ranges between a total of 40 and 50 pounds. These are also known as Channel catfish.
Unless it is a localized indigenous name, (common in the American South) they are known (properly) as "Blue Catfish", a specific species of catfish.
There are no size restriction for keeping saltwater catfish in Florida but be warned, they are not as good on the dinner table as freshwater catfish so I have been told.
(holding my hands out pretty wide) about this big.
La pasion
Up to 400lb
People, and other catfish if the one is big enough to eat the other... that's about all I could think of.
You will probably get infected by the bite, and have a bad cut.
Yes if the other fish can fit into its mouth! My catfish recently ate the 5" cichlid in the 90G tank. The cichlid was a little bit larger than the catfish when I first bought it (about 4") about 1.5 year ago, now the catfish is 9".