In my opinion, whilst not looking as pretty as the female fish, the male tench is very likely the hardest fighting coarse fish on a size for size basis in the country. Whether it's those huge ventral fins that do it I dont know, but I've had some monumental scraps with quite modestly sized male tench in my life. And I'm sure lots of others have too.
The hardest fighting tench I ever hooked was a 6 1/2 pound male fish from an Oxfordshire gravel pit using 6 lbs line, Avon rod and 5 lb hooklength. After 15 minutes by my watch the tench had still not tired, and that's a long time to play any fish.