What is the opposite of albinism?

The opposite of albinism is melanism. Melanism is a genetic condition that causes an excess of melanin in the skin, fur, or feathers of an organism, resulting in a darker, often black coloration. This darker pigmentation can provide certain advantages to the organism, such as increased camouflage in certain environments or better heat absorption in colder climates. Melanism is commonly seen in various species of animals, such as black panthers, black squirrels, and black jaguars.