Belacan (also spelled belachan, blachang, balachong) is a Malay condiment prepared from fermented krill.

To prepare belacan, fresh krill are mashed into a paste and buried for several months. The fermented krill are then dug up, fried and pressed into cakes.

Notoriously pungent, belacan is used as an ingredient in many dishes, or eaten on its own with rice. A common preparation is sambal belacan, made by mixing belacan with chilli peppers, minced garlic, shallot paste and sugar.

Belacan is related to Thai fish sauce, the Indonesian trassi, and the Philippine bagoong.