Whether you are a casual admirer of fishes, a serious enthusiast, or somewhere in between, it is very important to have four basic anatomical directionalities memorized. They also apply to most other animals within zoology.
Anterior - describes the direction towards to the front
- the anterior region is also the cranial region, or the rostral region, where the head and nose are found.
Posterior - describes the direction towards the rear
- the posterior region is also the caudal region (think of the caudal fin, also known as the tailfin)
Dorsal - describes the direction towards the back (spinal region)
- the dorsal region is often described as the topside for fishes, as their backs are nearer to the surface of the water. But don't be confused! Think of a seahorse that has its head closer to the surface more often than not - the dorsal region of that fish faces laterally, or sideways, and is not "topside" like most fishes.
Ventral - describes the direction towards the belly
- the ventral region usually holds pelvic and anal fins, and the urogenital and anal secretory passages (the cloaca or anus).