About the Game
Fish Tank is a live mechanical game from 155.io. A real coin drops into an actual water tank each round, and players bet on where it lands: the left or right side of the tank, inside a treasure chest, or in a white or red cup, with the outcome settled automatically once the coin comes to rest.
According to 155.io’s official documentation, Fish Tank carries a 90.09% base RTP across its markets, rising to an effective 91.10-92.12% once occasional Lightning Round boosts are factored in, with a maximum base win of 50x the stake.
Betting Markets
Fish Tank offers five outcomes with different payouts reflecting how likely the coin is to land there. Left side and right side each pay 2.26x, the safest bets. The treasure chest pays 8x, the white cup pays 12.36x, and the red cup, the hardest outcome to hit, pays the maximum 50x, all at a consistent 90.09% RTP.
Occasional Lightning Rounds can boost a winning bet further, up to a maximum of 250x on the red cup when a Legendary-tier boost lands, since the red cup, white cup, and treasure chest are the three outcomes eligible for the game’s rarer boost tiers.
Fairness & Distribution
Because the coin’s landing position comes from genuine physical motion rather than a random number generator, Fish Tank’s fairness rests on the same real-world-observation principle used across 155.io’s catalog, with each round’s outcome independently verifiable through the studio’s provably fair system. Rounds are cancelled and bets refunded automatically if technical issues prevent a result from being verified with certainty. 155.io distributes Fish Tank through the Hub88 aggregator and direct operator integrations.
RTP, Volatility & Where to Play
With a 90.09% base RTP and medium volatility, Fish Tank balances frequent smaller wins on the side bets against a real shot at 50x on the red cup, all within fast, continuously-running rounds.
Fish Tank is available at crypto casinos carrying 155.io content. For the studio’s full lineup, see our 155.io provider page and our CCTV casino games guide.
Max Ledger
Casino and gaming expert
Max Ledger is a crypto and online casino specialist who has personally reviewed 20+ crypto casinos on this site, covering blockchain gambling platforms, bonus structures, and provably fair gaming.