Fish Tank launched in December 2025 and is one of 155.io’s oddest ideas. A precision coin-drop machine hangs above a lit aquarium and releases coins around the clock. Each coin sinks through the water, past the fish, and settles somewhere on the bottom. You bet on where.
Founder Sam Jones has said the idea came from TikTok, where simple fish-tank prize games were blowing up. The studio’s response was to build a fully live, mobile-first version for online casinos.
How Fish Tank works
- Pick a landing spot: the left side, the right side, the treasure chest, the white cup or the red cup.
- Place your bet before the drop.
- Watch the coin sink. The water and the fish make every drop a little different.
- Result. Where the coin settles decides the payout.
There’s an auto-bet option if you’d rather sit back and watch.
The real odds
Every option returns 90.09%, so you can work out each one’s true chance from its multiplier:
| Landing spot | Pays | Chance |
|---|---|---|
| Left side | 2.26x | 39.9% |
| Right side | 2.26x | 39.9% |
| Treasure chest | 8x | 11.3% |
| White cup | 12.36x | 7.3% |
| Red cup | 50x | 1.8% |
Left and right together cover about 80% of drops. The red cup is the long shot, at roughly one drop in 55.