Tether (USDT) is now available on Statemine. You can find their official announcement here.

USDT was made into a sufficient asset with Referendum 197, which means that the receiver account doesn't need to hold an existential deposit of at least 3.33 microKSM (0.00000333 KSM). 

WARNING! Anyone can create an asset on Statemine, with any name and symbol. Therefore it is important to make sure you are transferring the official asset, which you can determine by looking at the unique asset ID. For Tether, this ID is: 1984

NOTE: Even though these instructions are for transferring USDT, they apply to transferring any other asset too, on both Statemine and Statemint.

If you want to learn more about these two system parachains, you can read this article.

1. First, switch to the Statemine network.

2. Next, navigate to the Network > Assets page and click on the Balances tab. Select the correct asset ID from the drop-down menu. 

3. Click the "send" button. Then enter the receiver address and the amount to transfer.

4. Sign and submit the transaction, and that's it! Remember that the assets will show up on the recipient's Statemine account, and not on the Kusama relay chain.