Hi Hive account@sarah249, thanks for your feedback.

This opportunity does not factor in any costs. With these fees in mind there is still an arbitrage opportunity. We are currently looking into incorporating the fees for the transactions on exchanges. However, we also recognise that this is one of multiple possible trading scenarios. For example, one scenario represents the opportunity where a trader already has BTC on bittrex, and BTG on bitbay. Here there is no need to withdraw or transfer, and one simply executes the trades on the respective exchanges.

To summarise, you're correct that the final profits would be lower when including all fees, and this does not factor in the time to transfer between exchanges, which would result in price movements. The perfect arbitrage scenario would have zero transfer time between buy/sell orders by having the currencies already on the respective exchanges.