Anorexia is often a common problem in newly acquired elasmobranches. Capture, shipping, stress, foreign foods, new environment, exposure to medications, delivery of pups are all possible reasons why your shark won't eat. Short periods of fasting should be closely observed, but several weeks of anorexia, lasting a month, are a cause for concern. You need to consider the size of the animal and physical state when deciding to force feed. I would give a large inactive wobbegong a much longer leash...