Nice
A nice relaxing game. Loads of fun!
A few suggestions:
1. Maybe when you eat enough smaller fish, you grow in size and can start eating more and more fish that are smaller than you. For example, those Green Sharks are bigger than you, but if you eat enough fish you can become bigger than them and eventually start eating the Sharks for more points. A system like this would be cool.
2. Power ups? Maybe like invulnerablity and bonus multipliers
3. Have a little icon at the top that shows the previously ate fish, this will help the player track what fish they just ate so they can get in a multiplier. Like I ate a Red Fish but I easily forget I just ate a Red one, so I lost my multiplier.
4. Have a shop that sells "Fish Food" for maybe 1000 points a piece. You throw one piece and it attracts all the bigger fish towards it for a brief time, allowing you to gobble up the smaller fish for points.
Good work though!!!