Fiberglass fish arrows are solid, and yes, Monty Browning used a fiberglass fish arrow to take his bear. I believe he also uses them on moose. Regardless, target and hunting fiberglass arrows are hollow. The tolerances on some of the better brands of fiberglass shafts, like micro-flite, are quite good. They were/are consistent in weight, spine and straightness. They do not take a set or get out of straightness. They're either straight, or broken, like carbon.
That being said, aluminum shafts were even straighter. Not really tougher though. Aluminum bent fairly easily, and though it could be restraightened, usually not to original specs. Fiberglass had a tendency to split on the point ends when a solid object was hit. The insert would get driven back into the shaft, splitting it. The same thing can happen with carbons today, though carbon is much tougher. Back in the day, no one thought of footing fiberglass with a piece of aluminum shaft, as they do with carbons now. That would have solved the splitting problem for fiberglass shafts just as it has for carbons.
Fiberglass shafts are a good arrow material; they just lost out to aluminum. In today's market, they couldn't compete with carbon. Still good shafts though. When I find some in my spine weight, I buy them and shoot them.