| Barcelos | |
| Settlement Type: | Municipality |
| Official Name: | Municipality of Barcelos |
| Nickname: | "Capital do peixe ornamental" ("Capital of the ornamental fish") Cidade menina ("Girl City") |
| Mapsize: | 250px |
| Pushpin Map: | Brazil |
| Pushpin Map Size: | 250 |
| Pushpin Map Caption: | Location in Brazil |
| Subdivision Type: | Country |
| Subdivision Type1: | Region |
| Subdivision Type2: | State |
| Subdivision Name: |  Brazil |
| Subdivision Name1: | North |
| Subdivision Name2: | Amazonas |
| Leader Title: | Mayor |
| Leader Name: | José Ribamar Beleza (MDB) |
| Established Title: | Founded |
| Established Date: | May 27, 1758 |
| Area Total Km2: | 122,475.728 |
| Population As Of: | 2020 |
| Population Note: | [1] |
| Population Total: | 27,638 |
| Population Density Km2: | 0.21 |
| Timezone: | AMT |
| Utc Offset: | -4 |
| Coordinates: | -0.975°N -62.9239°W |
| Area Code: | +55 92 |
| Postal Code Type: | Postal Code |
| Blank Name: | HDI (2000) |
| Blank Info: | 0.593 – medium[2] |
Barcelos (also Barcellos), formerly Mariuá, is a municipality located in the state of Amazonas, northern Brazil. Its population was 27,638 (2020) and its area is 122476km2,[3] making it the second largest municipality in Brazil (behind Altamira, Pará), equivalent in size to New York state in the United States and slightly larger than North Korea.
Since 1994, Barcelos has been the host of an annual festival celebrating ornamental fish,[4] which is a significant source of income for the region. Project Piaba uses Barcelos as the starting point for their annual research expedition into the Rio Negro area.[5]
Barcelos was originally named Mariuá, village of the Manaus Indians. When the captaincy of São José do Rio Negro was formed in 1755, Francisco Xavier de Mendonça Furtado, Governor General of state of Grao Para e Maranhao chose the aldeia de São José do Javari, a village founded by Carmelite Friar Matias São Boaventuras in 1728 near the mouth of the Javari River, as its capital. It was the capital of the captaincy of São José do Rio Negro from 1755–1791, and again from 1799–1808.
The municipality area is 122,476 square kilometres (47,288 sq mi), making it the second largest municipality in Brazil (behind Altamira, Pará), equivalent in size to New York state in the United States and slightly larger than North Korea.The municipality contains part of the Amanã Sustainable Development Reserve.It also contains part of the Amazonas National Forest.It contains the Rio Unini Extractive Reserve, created in 2006.
The climate reflects its vegetation being tropical rainforest or equatorial (Köppen: Af), like the rest of the Amazon Basin.[6]
The city is served by Barcelos Airport with scheduled services to Manaus.