Hello, I have been going to Coggshall Park for years and there is no fishing allowed and for good reason. Coggshall park is home to many ducks, geese, wild birds, turtles and ect which has led to a major increase in pollution from the feces of these animals. Furthermore, people go there to feed the birds which creates a bacteria. I am sure you would catch and release any fish caught at Coggshall, but honestly the hazard of just fishing in this water isn't worth the health risk.
I would call Fitchburg city hall and ask them. Since it's a city park.
Thanks! Your answer is awaiting moderation.