Canadian bought BTC on cex.io in USD - how do I deal with them to not lose money with CAD-USD exchange rate?
Even the Canadian exchange places like quadrigacx or Einstein deal in US funds for the sake of trading.
You spend CDN to get US so you can buy and trade.
   If I could give you a piece of advive...  trade your bitcoin for LITECOIN before sending it to a different exchange place. Bitcoin will cost about $40 in network fees to send. Litecoin is pennies.
    After that  you send from your litecoin wallet on cex to your litecoin wallet on Quadriga. 
Only ever send lite to lite , btc to btc etc...
        Go to quadriga and fund your account. Select litecoin. It will show your wallet address. Copy exactly.
Go to cex  litecoin waller. Hit "send litecoin" put the litecoin address that you copied from quadriga. And send funds.
You may get an email asking you to confirm.  Every site is different. It will take about 20 minutes. (6 confirmations)
It will then show up in quadriga.