my best ever is a black carp (some sort of carp but a bit slim and much stronger).
the 9.5kg one was caught on a 4.5m rod with 4.5m 2.4lb line( no reel) this was a miracle and no one has ever broken this record in China where i made it.
back in australia, i have once caught a stingray around 25kg on 6lb leader and 4lb fireline. the reel was a cheap shimano