However, there are a couple of things that might look like coughing:
* Expelling water: Fish can sometimes expel water through their mouths, especially if they've accidentally taken in a mouthful of water. This can appear like a cough, but it's simply them clearing their mouths.
* "Coughing" to clear the gills: Fish may also move their gills rapidly, often accompanied by a clicking sound, to remove debris or parasites from their gills. This behavior is not technically coughing but is similar in function to clearing the airways.
In short, fish don't cough in the same way as mammals. What might look like coughing is likely them clearing their mouths or gills.