There should be a fish trading post. It could be like, ten sea snails for one goldfish. Ten goldfish for one shrimp, ten shrimp for one icefish. That way, if the market prices are low, you can still get amazing fish that sell high.
Also, in the case of the game industry, DRM is only added to try to stop pirates. As more and more people switch to pirates, game companies try to add more and more DRM to try to stop this. Don't be like "OMG UBISOFT Y U ADD DRM I SHALL NOW PIRATE GAEM" because it only hurts the industry even more.