Hair -shedding like a dog

I'm a 53 year old male with most of my hair, but with a moderate receeding hairline, although I suspect it might be thinning. And the individual hairs seem to be thin and brittle. And everytime I run my fingers through the hair I can bring out a couple of strands, while my brush fills up rather quickly, and my bathroom looks like a barber shop. This has been going on for several years
I eat lots of fish - could that be a problem?