It's called Fishin’ 2 Go
You basically hold your phone just like a fishing rod, and mimic the same movements that you would in real life when casting, retrieving the lure, and fighting the fish.
Fishin’ 2 Go takes advantage of your phone's accelerometer and vibrator to give you the most realistic fishing experience possible.
(from the blog for Fishin'2 Go)
Features: * Physical controls using the accelerometer (casting, etc)
* Realistic fish behavior & intelligence * 5 freshwater locations
* 3 saltwater locations * Sound effects & in-game fish finder
* Over 50 different fish species, from bluegill to mammoth-sized blue marlins
* Select from over 30 various lures & baits, and customize your tackle set-up
* Compete with friends and family by saving your best catches under your own name
* View top catches by species and location
* New features are added on a regular basis!
Look up Fishin' 2 Go in the Android Market app to download the free LITE version for a taste of the action. If you like it, the FULL paid version is available for $2.25, and offers all of the features above. Visit the Fishin' 2 Go Blog for screen shots, news, and species list: http://fishin2go.wordpress.com