Ichthyosis – also called fish scale disease – is a group of skin diseases, which are characterised by xerosis and scaling. Most commonly, the diseases are genetically inherited, but an acquired type also exists. Ichthyosis vulgaris (IV), is the most common type, affecting 1:250 individuals. Diagnosing IV can be challenging, because its clinical features are subject to great variation, ranging from mild cases with slight xerosis to severe cases with marked scaling and formation of fissures. In this review, IV and its most relevant differential diagnoses, X-linked ichthyosis, autosomal recessive congenital ichthyosis and acquired ichthyosis are reviewed.