Okay, I know that this basic premise is not new. The player is a small fish, and it eats smaller fish to grow bigger, at which point it can eat more fish, and grow bigger still. The circle of life continues, and we mostly ignore it.
Most games with this idea stop once the biggest fish is eaten, but not Tasty Blue. In a manner reminiscent of Katamari Damacy, the protagofish continues to grow, and will eat anything smaller than it, including sunken treasure, mermaids, and eventually helicopters. Nothing can stop the hunger of the little escaped goldfish, it seems.