Perpetuals have their own fee structure that can be viewed here. 

Note: Fees are charged in GUSD.

The fees you pay will depend on your volume traded on the Gemini Derivatives sub account as well as whether you are trading as a “maker” or a “taker”. Every transaction has 2 sides, one side is a maker and the other a taker. Your position as maker or taker and the associated fees you pay are specific to each trade you execute.

• If you send an order to the exchange that will need to wait for someone else to come and trade against it, for example a Limit Buy order with a limit below the current best ask or a Limit Sell order above the current best bid, then you are deemed a maker. 
  
  
• If you actively trade against resting orders on the order book, for example, by using market orders or limit orders with limits through the best bid or ask then you are deemed a taker.