Matsya (Pali: Macchā) was an ancient Indo-Aryan tribe of central India whose existence is attested during the Iron Age.

Later Puranic texts such as the Mahābhārata connects them with the Trigartas and the Caidyas, and the Manu-Saṃhitā lists the countries of the Mātsyeyas, the Śūrasenakas, the Pañcālas, and of Kuru-kṣetra, as forming the Brahmarṣi-deśa (the holy enclave of the brāhmaṇa sages).

[1] The later history of Matsya is not known, although the Buddhist Aṅguttara Nikāya included it among the sixteen Mahājanapadas ("great realms"), which were the most powerful states of India immediately before the birth of the Buddha.

[5] The Matsya state in the Mahājanapada period archaeologically corresponds to the Northern Black Polished Ware archaeological culture which in the western part of the Gaṅgā-Yamunā Doab region succeeded the earlier Painted Grey Ware culture, and is associated with the Kuru, Pañcāla, Matsya, Surasena and Vatsa Mahājanapadas.

[6] Unlike other states of central India who abandoned the kingdom form for a gaṇasaṅgha (aristocratic republic) mode of government during the late Iron Age, Matsya maintained a monarchical system.