Overview
Aquarium is a Cardano payment tool that lets people pay network transaction fees in any native Cardano token, not just ADA. It's useful for anyone who holds a project token but no ADA, or for projects that want to spare new users from buying ADA before their first action. What makes Aquarium different is that the same app also handles scheduled payments — one-time or recurring — so users can queue a transaction in advance and let the network execute it for them1.
Aquarium is built by FluidTokens, an Italian-Swiss team that ships a family of Cardano DeFi protocols including lending, renting, and staking products. The "babel fee" idea behind Aquarium comes from a Cardano research paper by Input Output Global, which proposed letting users settle network fees in tokens other than ADA2. Aquarium is the live consumer-facing implementation of that idea.
Key Features
- Pay fees in any Cardano token. Users can send a transaction without holding ADA — the network fee is covered by a fee tank in exchange for the user's chosen native token1.
- Fee tanks for liquidity providers. Anyone can lock ADA into a fee tank that sponsors other users' fees. In exchange, the tank earns a reward in the tokens it accepts, providing a way to put idle ADA to work3.
- Scheduled and recurring payments. Users define a transaction once and a decentralised network of Aquarium nodes competes to execute it at the right time, useful for one-off future payments or recurring on-chain actions3.
- Independent third-party audit. The Aquarium smart contracts have been reviewed by Anastasia Labs, with the final report published openly on the FluidTokens site4.
- Open-source validators. The Aiken-written smart contracts that power tanks, rules, and node coordination are published in the FluidTokens GitHub organisation3.
What to Expect
The Aquarium homepage groups the product into three clear flows: a babel-fee form, a fee-tank setup, and a transaction scheduler. Each one starts the same way — connect a Cardano wallet (a self-custody app that holds your keys), then pick the token you want to use. The "Try Babel Fees" form is the most accessible entry point and walks a first-time user through choosing what to send and which token to pay the fee with.
For projects and DApp builders, Aquarium fits the payments-and-accounting part of the Cardano stack. Integration is API-based; access is gated behind the FluidTokens Discord rather than a public developer portal1. Day-to-day support, technical questions, and integration requests all run through the parent FluidTokens community channels — there is no Aquarium-specific X account, Discord, or blog. Documentation lives at docs.fluidtokens.com, where Aquarium sits alongside FluidTokens' lending, renting, and staking protocols5.
