The table below shows which fiat currencies can be used for arbitrage trading between supported exchanges. This table helps to understand which fiat currencies you should have to prospect for possible arbitrage opportunities.

Please note that you should also have the same market available between them. For instance, to complete an arbitrage trade between Bitstamp and Bitfinex you can store either USD or EUR fiat currency, and both exchanges should have BTC/USD or BTC/EUR markets available.