Introduction

• The brain is enclosed in a cranium, which is cartilaginous in elasmobranchs and bony in teleost.
• Generally, the brain of fishes is relatively small in comparison to their body size and hence the brain does not occupy the cranial cavity completely, leaving a small gap, which is filled with a sort of gelatinous matrix.
• The brain is soft and white and covered by an extensive network of blood vessels called choroid plexi.