The piscivorous herring, Chirocentrodon bleekerianus, folds its prey in half in order to be able to swallow fish of a similar size to itself.
The pristigasterid clupeiform fish from the South West Atlantic only grows to 10cm/4" but manages to swallow proportionally large fish and shrimps by arranging them carefully as they are swallowed.
According to a report in the Brazilian Journal of Biology, the fish folds its prey in half so both the head and the tail point forwards towards the predator's head.
The researchers have also seen this behaviour in some characins which share the same canine dentition seen in Chirocentrodon.
For more details see: Sazima C, Moura RL, Sazima I (2004) - Chirocentrodon bleekerianus (Teleostei: Clupeiformes: Pristigasteridae), a small predaceous herring with folded and distinctively oriented prey in stomach. Braz J Biol. 2004 Feb ; 64(1): 165-8