In what computer game are there big fish that attack your smaller fish?

I played a really fun, down-loadable computer game one time where you can buy fish and stuff for you tank like snails and oysters. Also, big, meat-eating fish can come and eat that fishes. Please let me know what game this is.In what computer game are there big fish that attack your smaller fish?
I think you are thinking about Insaniquarium...if not, it is very similar.