The term for the action a fish uses to "gasp" for air is called **[buccal action pumping][1]**.  I am wrapping up a conservation biology degree with focus in fishery science at CSU.  Here's some information:

**dual pump**: buccal and opercular action operating in tandem drives water in a nearly continuous unidirectional flow across the gill curtain between them

- the suction phase begins with compressed buccal and opercular cavities and closed valves
- as the buccal cavity expands, the internal oral valves open and water moves into the buccal cavity and across the gill curtain
- during the force phase, the oral valve closes and water is forced out through the opercular valve

Source: https://www.shsu.edu/~bio_mlt/Chapter11.html

A good image of this action can be found [here][2]:

[![enter image description here][3]][3]


  [1]: https://www.wikiwand.com/en/Buccal_pumping
  [2]: https://www.pathwayz.org/Node/Image/url/aHR0cHM6Ly9pLmltZ3VyLmNvbS9yc01Kd1RNLnBuZz8y
  [3]: https://i.sstatic.net/s9dCb.png