There are several popular virtual currency exchanges in Rio de Janeiro, Brazil, where individuals can buy and sell various cryptocurrencies. Some of the most used exchanges in the city include:

1. Mercado Bitcoin: One of the largest and most well-known cryptocurrency exchanges in Brazil, Mercado Bitcoin offers a wide range of cryptocurrencies for trading, as well as competitive fees and a user-friendly platform.

2. Foxbit: Another popular option for cryptocurrency trading in Rio de Janeiro is Foxbit, which offers a secure platform for buying and selling digital assets such as Bitcoin, Ethereum, and Litecoin.

3. BitcoinToYou: BitcoinToYou is another prominent virtual currency exchange in Rio de Janeiro, offering a simple and intuitive trading platform for individuals looking to invest in cryptocurrencies.

4. Coinext: Coinext is a Brazilian cryptocurrency exchange that provides a range of digital assets for trading, as well as advanced trading tools and features for more experienced traders.

5. BitCambio: BitCambio is a popular exchange in Rio de Janeiro that offers a variety of cryptocurrencies for trading, as well as competitive fees and a straightforward registration process.

These are just a few of the most used virtual currency exchanges in Rio de Janeiro, Brazil. It's important for individuals to research and compare different exchanges to find the one that best meets their needs in terms of security, fees, and available cryptocurrencies.