WTF, right?
I scanned this photo from a 1963 book called "The Fishes" from Time/Life's Nature Library series. Apparently the hoods on the fish block their lateral line, so they no longer swim away when someone sticks their hand in the tank. But I think it is more likely that their loss of reflex is due to excessive brainwashing by the Hooded Fish Cult.
I wanted to find a scientific paper to go with this image, but a web search of the supposed researcher "Dr. Theodore Walker" yielded few results related to this particular picture of the hooded fish cult.