If you're encountering an "insufficient fees" error when trying to send USDC on the Arbitrum network, it likely means that you have enough USDC in your wallet to cover the transaction amount but not enough Ethereum (ETH) to cover the gas fees required for the transaction to be processed on the Ethereum blockchain.

When you're using decentralized finance (DeFi) platforms or layer 2 solutions like Arbitrum, you typically need to pay gas fees in ETH to interact with the Ethereum blockchain. Even though you're sending USDC, the transaction still needs to be processed on Ethereum, which requires ETH for gas fees.

You'll need to ensure that you have enough ETH in your wallet to cover the gas fees for the transaction. You can acquire more ETH and then try the transaction again. Make sure to check the current gas prices to estimate the appropriate amount of ETH needed for the transaction to go through smoothly.