Take your beveler and carefully bevel around the fish as outlined in red in the instructional picture shown here.
Remember to be careful in small and tight areas around the fish. If you are nervous or do not feel confident with your beveler. There are two options available to you. One you can practice with your beveler of choice until you become more proficient OR you can take the easy way out and deploy your modeling spoon. Just remember to take your time.
With your modeling, create some sidelines on your rocks to give it a roundness effect. Also, use the modeling spoon to complete the extensions of your cut lines. These are identified as dotted lines in your pattern as originally marked on your leather piece.