We present the design and evaluation of an exhibit on the consequences of overfishing that we deployed at a local aquarium. The exhibit, Fishing with Friends, is a multiplayer game in which visitors compete to earn money by catching fish. As the game progresses, overzealous fishing results in damage to a simulated ocean ecosystem. Our goal is to encourage visitors to reflect on damage caused by overfishing and discuss strategies to preserve shared ocean resources. Aquariums are leading the effort to inform the general public about issues of marine sustainability. However, it is challenging to make these complex topics engaging and accessible to a diverse audiences in real-world settings. We conducted a study with 523 visitors at the aquarium to evaluate our design. Results from a questionnaire suggest that engagement with Fishing with Friends improved our target audience's awareness of environmental issues compared to those who were not exposed to the game. Our results also highlight challenges of using interactive tabletops displays in crowded and chaotic exhibit halls. On average, 52.6 visitors interacted with the game every hour that the exhibit was on display; this rapid flow limited engagement and presented unique design challenges that we discuss in this paper. Future work will be needed to assess longer term impacts and to compare game play to other forms of interactive and non-interactive interventions.