Blackhole swap is a decentralized exchange on Avalanche C-Chain where your wallet trades tokens against available on-chain liquidity; you can also supply assets to a pool. To make the trade, use Blackhole swap with a C-Chain wallet; the Blackhole crypto exchange also lets you provide liquidity.
Connect a wallet such as Core or MetaMask to Avalanche C-Chain, hold the token you want to sell, and keep some AVAX for transaction gas. Avalanche mainnet’s C-Chain ID is 43114. blackholeswap.app is the service for the C-Chain swaps and liquidity provision discussed here.
For an illustrative USDC-to-AVAX trade, enter an amount of USDC and examine the resulting quote before signing. If this is the wallet’s first use of that token with the exchange contract, you may need to approve an ERC-20 allowance in a separate transaction. Ethereum’s EIP-20 standard defines that allowance: it authorizes a contract to spend up to the approved amount, while the swap itself is a later action.
Before submitting, check these five details:
The exchange uses liquidity supplied to pools to fill the trade. In a typical constant-product pool, adding USDC removes AVAX and shifts the pool price as the reserves change; a route through multiple pools repeats that process at each hop. The actual output depends on available depth, the route, and pool fees, so the number of tokens in your wallet is the result to judge.
Suppose, purely as an example, a pool holds 100,000 USDC and 1,000 AVAX. A 1,000 USDC purchase would return about 9.90 AVAX before fees under the constant-product formula, versus 10 AVAX at the starting pool price. That roughly 1% difference is price impact already present in the quote. A 0.5% slippage limit addresses further movement after the quote; it does not remove the quoted price impact.
You can trade a C-Chain token when usable liquidity exists for it, directly or through another token. A token’s presence in your wallet does not guarantee a viable route, and a route with little depth can quote a poor rate even when it technically works. For a small pool, compare the output for your full amount with a smaller trade; a sharp deterioration shows that trade size is driving the price.
Check the contract address rather than relying on a ticker. Native, issued, and bridged versions of an asset can have similar names while remaining distinct tokens. Assets held on Avalanche’s X-Chain or P-Chain are not C-Chain tokens available to a C-Chain swap without a separate transfer.
Providing liquidity is a different decision from trading. Depending on the pool design, you may need both assets in a specified ratio and receive a position representing your share. That position can earn trading fees, but its token mix changes as traders use the pool. Compare its eventual value with simply holding the deposited assets; fee income does not guarantee that the liquidity position comes out ahead.
The cost combines the pool’s trading fee, price impact, and C-Chain gas; an approval can add another gas payment. Pool fees vary by design and are often on the order of 0.05% to 1% per pool as a general AMM range, not a stated fee for this service. A route crossing two pools can incur a fee at each hop, so judge the final quoted output rather than one percentage alone.
Gas is charged in AVAX even when you sell USDC. Avalanche Builder Hub describes C-Chain fees as gas used multiplied by the transaction’s effective gas price, which changes with network demand. As an illustration, a swap using 150,000 gas at 25 nAVAX per gas costs 0.00375 AVAX; the actual amount depends on the transaction and prevailing gas price.
For a modest trade, price impact can outweigh both gas and the pool fee. If doubling the trade size makes the rate materially worse, splitting it may improve execution, but each additional swap pays gas and exposes you to a fresh market price. Compare the total tokens received after those costs before splitting an order.