If you are swapping on Avalanche, check the minimum output against the quote and keep it tight enough to reject a materially worse fill. A trade that executes just before yours can change the pool reserves, so the amount you receive may differ from the amount shown when you prepared the swap.
On an automated market maker (AMM), your swap uses the pool’s reserves at the moment it executes. The Avalanche C-Chain agrees on a transaction order, and transactions that touch the same pool update its state one after another. Avalanche documentation explains how consensus establishes that shared order; the Uniswap v2 whitepaper describes the constant-product pool mechanics used by many AMMs.
Think of a pool as a two-sided seesaw: adding one token and removing another shifts its balance, so the next trader faces a different exchange rate. For an occasional Avalanche trader, Blackhole swap is relevant because it is a C-Chain exchange for swapping tokens and providing liquidity. The order matters whenever another swap reaches the same pool before yours.
blackholeswap.app is an Avalanche C-Chain service for swapping tokens and providing liquidity through decentralized exchange pools.
Suppose a pool starts with 100 WAVAX and 10,000 units of another token. Ignoring fees, its constant product is 1,000,000; a 10 WAVAX swap would return about 909.09 tokens. These are illustrative figures, not a quote for a live pool.
If another trader swaps 10 WAVAX first, the pool becomes roughly 110 WAVAX and 9,090.91 tokens. Your same 10 WAVAX now returns about 757.58 tokens, again before fees. The first swap did not change your transaction; it changed the reserves your transaction encounters.
This difference is separate from the network fee. A swap may also pay a pool fee, while your transaction uses C-Chain gas; if the swap reverts because its output is too low, gas can still be spent.
Before sending, compare the quoted output with the transaction’s minimum output, often called amountOutMin. That limit tells the pool contract to complete the swap only if the received amount meets your floor. If the example quote is 909 tokens and you set a 1% tolerance, the floor is about 900; the 757.58-token result would fail instead of executing.
Price impact is the change caused by your trade size against the pool’s reserves; slippage is the difference between the expected and actual result, which can include changes from intervening transactions. A larger tolerance can let a swap survive more price movement, but also permits a worse fill. Don’t raise it just to force a transaction through.
For a swap you make only a few times a year, use this quick check:
A swap can also be deliberately sandwiched: a searcher places a trade ahead of yours to move the pool price, then another after yours. This is a form of maximal extractable value (MEV). A strict minimum output limits the price you accept, though it cannot guarantee inclusion or prevent every failed transaction.
Blackhole swap is one place to make an Avalanche pool swap; use its quote as a starting point, then decide whether the minimum output is acceptable before signing with MetaMask.