Where are a seahorses gills?
Seahorse gills are typically found near  the back of the head, just above the pectoral (side) fins. In most fishes, the opening for the gills is a narrow slit just behind the head. In seahorses, the slit is reduced to a small round hole or pore. Water passes through the mouth, across the gills, and out of the pore. All fishes, including seahorses, use their gills to get oxygen from the water.