Each coin on Prestmit has its own minimum trade amount. The minimum ensures the transaction is large enough to cover blockchain network fees and still be processed efficiently.
To see the current minimums for each coin, go to "Crypto Wallet" in the app and select the coin — the minimum is shown on the wallet page.
Please Note: Sending an amount below the minimum for a coin will result in the transaction not being processed. Always verify the minimum before sending. There is no upper limit on how much crypto you can sell.