Ram ventilation is a type of gill ventilation used by some fish species, especially those in the marine environment. Some classic examples are the tuna, swordfish and shark.

Ram ventilation consitutes swimming in relatively straight lines at a high rate of speed with the mouth open. This forces water through the mouth and over the gills, meaning the fish can breathe passively while swimming. This has the added benefit, for some species (tuna, whale shark), of providing food. Those species which are zooplanktivorous will catch animal particles in the water on their gill rakers, and transfer this food into their oesophagus.