RCWeb Flappy Fish Control turns a phone into a one-button controller for the shared Flappy Fish screen.

Open /flappy-fish/ on the main screen first, then scan its QR code with your phone. The phone opens /flappy-fish-c/ in the same room.
Tap JOIN to enter the school. Once you are assigned a fish, the button changes to SWIM.
Tap SWIM to push your fish upward on the shared screen. The current pulls your fish downward between taps, so steady timing matters more than tapping as fast as possible.
The controller shows your fish, score, win count, and current status. The game itself runs on the shared screen, so keep watching the main display while you tap.