Puffer doesn't seem interested in the shrimp at all, but prefers instead, pregnant guppies.
Guppies are fairly easy to breed and, I swear, can live in a dirty toilet. This tank was full of them and ghost shrimp before I cleaned it out. The water was absolutely brown with tanic acid and dissolved sludge.
Puffers belly will turn white just prior to hunting. He then sneaks up on a female guppie while she is giving birth, and grabs her by the vent, devouring the babies by sucking them from the mothers womb, then he begins traveling up and down in the tank shaking the female as he chews, never releasing until after he had eaten everything and has sucked the skull dry of its contents including the ever so delicate eyes.