Not sure how much the snakes bite will hurt the snakehead which is pretty robust at similar weights it will have a smaller head and it's jaws seem more suited for grabbing than tearing which the snakeheads Jaws are adapted for.
Elephant trunk snakes weigh between six and 22 pounds on average.
The snake can remain submerged up to 40 minutes without coming up for air.
Williams , Jeff Boundy 2014.
Though it is possible of the snake manages to coil the fish first, there's also possibility that the fish is still able to bite the snake's body or head.
Life is Short, but Snakes are Long.