The Blackspotted Puffer (or Arothron nigropunctatus) is a medium-sized fish found in both Endless Ocean games.
"These unusual-looking fish are quite round and lack any sort of pelvic fin. They are usually grey with black spots and can be seen near Blue Holes in the spring."
"This round fish’s face looks a little like a dog’s from the front. It can be grey or yellow but it is always covered in black spots. When startled, it draws water into its stomach, inflating itself and making countless tiny spines on its body stand up. Although it usually swims at a leisurely pace, it is capable of short bursts of speed when it feels threatened."