I ran a quick experiment on that with a tank full of canary fire-arrows some time ago. I discovered that no matter how many times I used it, the mutation pool was very small. In other words, I could get either fruitfish or goldshark but no other body type, or I could the orange fin or the wasp fin but no other fin type.

After I finish the current two games I might run a full-scale experimentation... it's a project on the back burner for now, though.