Fish can cough. They do this to dislodge items from their gills. They also do this to expel air. A fish can cough, hiccup, and breathe. They can do all of this while they are under water. Fish has been known to cough up food and even hooks. Sensors have been placed in many aquariums to monitor the behavior of fish. The fish has been monitored by many experts. Their movements have been recorded, as well many of their actions. This includes the act of coughing.