How many layers of gills are on each side the fish?

The number of layers of gills on each side of a fish can vary depending on the species. However, it's not quite accurate to say there are multiple *layers* of gills.

Here's a breakdown:

* Gill Arches: Fish have multiple bony or cartilaginous arches on each side of their head, usually 4-5. These arches support the gill filaments.

* Gill Filaments: These are thin, feathery structures that extend from the gill arches. They are covered in a network of tiny blood vessels and are responsible for gas exchange.

* Gill Rakers: These are projections on the gill arches that help filter out food particles from the water.

So, instead of "layers," you could say a fish has multiple gill arches on each side, each supporting numerous gill filaments.

Let me know if you have any other questions about fish anatomy!