There is a very good lake for bass fishing in or around Chapala and Ajijic called Lake Agua Milpa. I have a good friend who would go there all the time who called it one of the best fishing spots he's ever been to. Lake Agua Milpa is a two-hour drive from Ajijic. There are cabins along the beachfront. It is up in the hills so there is not much around it. There are no cities that are near, but there a couple of little towns or "pueblos". The local people know the lake real well. There are guides who would take you to the lake. The fishing here is fantastic and the water is so clear.
Lake Chapala is a shallow lake and the water is not clear. There is no real fishing in Lake Chapala, but sometimes locals would fish off certain areas of the wharf.
In San Juan Cosala (a town adjacent to Ajijic), some people would do net fishing. The fish they catch is not good for eating not because of pollution, but more because of the mineral content such as mercury. However, the locals do eat fish that they catch.
The closest town from Ajijic that's beside the ocean is Manzanillo. The drive goes through Colima and is about three-and-a-half hours from Ajijic. Fishing in the Pacific Ocean is fantastic. Manzanillo is known for marlin fishing and game fishing.
(Fishing at Lake Agua Milpa, Mexico, pictured.)