In order to put your crypto fish token on sale on the integrated marketplace please enter the game and press "Sell" button on the information page of any of yours fish tokens.
Sending a fish to the market will freeze it for 7 days (it will be protected from attacks for this period). You are also not allowed using it to attack others while fish is on sale.
Anyone can buy the fish on the market by paying the price you named. After buyer transfers cryptocurrency you will receive Ether directly on your Ethereum wallet (one that owns the fish).
If the fish token was not sold for that period it will remain on the market until Seller will not Return it. After the fish token is returned it can be sent to the Market again or used to play the game as usual.
Commission of 4.5% will be paid by the Seller on a successful deal.