The fees are constantly changing because of the Bitcoin network. If you want to confirm the minimum fee at the moment of your transaction, you can contact the support team through the Live Chat on spectrocoin.com.
How retarded do you take your clients for? Having a static minimum fee of 0.001 which ammounts to ~222sat/b is not what you call constantly changing, while transactions with fees like 10sat/b go in the next block. Stop ripping off your customers, classic Lithuanian scammers.
Recommended BTC withdrawal fee is 0.001 BTC (set by default), however, you may also set it as 0.01 BTC in order to have your transaction proceeded even faster. It can be changed when you click on "Fee configuration" on the BTC withdrawal page.
The current fees are set in this range since the BTC network or blockchain is busy and if the fee is low, the transaction could take so long to be processed. At normal times, the fee is less and counted depending on the busyness of the blockchain. This is all done to ensure that funds will be processed quickly and there will not be frustration with funds not reaching the other end by the time agreed upon.