Personally, i do not use fiat on crypto exchange and this is not also available in my jurisdiction, so i do not pay tax, but i do not know if the fee deducted by exchanges are also used as tax by those exchanges.
The fees deducted from your trade is paid in tax but that is the tax payable by the exchange from their earning. They do not pay for you from your earning and from your fees. while if the exchange will be from your country and your country will regulate that exchange then they will have the duty to give the details and to collect the tax if they were asked from your country to do so.