Aquarius is designed to supercharge trading on Stellar, bring more liquidity and give control over how it is distributed across various market pairs. It adds incentives for SDEX traders ("market maker rewards") and rewards for AMM liquidity providers.
What is the biggest group aligned with the Aquarius mission of bringing more liquidity to the Stellar network? The answer is simple — the holders of the native currency of the network, Stellar Lumens.
Therefore Aquarius is airdropping 15B (15% of the AQUA supply) to XLM holders.
Update 12/21:
The community has voted for a proposal to change the snapshot date to January 15, 2022, at 00:00:00 UTC.
Update 04/22:
Rewards can already be manually claimed on a monthly basis. If eligible, you can claim your rewards via StellarTerm / Pending Payments.
So there is still time to complete the required steps.