「Fish emperor」is the STURGEON, the fish that gave us caviar. If you still believe that the Chinese sages did not mock everyone without exception, consider that the Chinese white STURGEON is a fish with four long barbels appearing as do a long mustache and beard whiskers, a perpetually-open highly-extensible wide toothless mouth, a bottom-feeder in the benthic zone of a waterway, sucking up whole and swallowing various small crustaceans, worms, larvae and snails from below the mud surface and sediment substrate. One of the oldest fishes still surviving both as individuals, and as a species with a long genealogical one of ancestors, virtually unchanged for 100 million years or so in the geological and fossil record, dating back to the Cretaceous period (the fish that resembles the emperor):
「Lake sturgeons can be huge, topping six feet (two meters) long and weighing nearly 200 pounds (90 kilograms). They are also extremely long-lived. Males may live some 55 years, and females can reach 150.」
[ https://environment.nationalgeographic.com/environment/freshwater/lake-sturgeon/ 2014-09-11 ]
In China as recently as 2012, specimens longer than 9 feet weighing over 1300 pounds have been caught, or not, since in 2013 one sturgeon was purportedly large enough to drag the fishing human into the river and kill him in a case of turnabout as fair play [ https://travel.aol.co.uk/2013/03/27/fisherman-dragged-to-death-giant-sturgeon/ 2014-09-12 ]
One must wonder why the Chinaman did not simply let go of his rod, but obviously that thought had never before occurred to him.
「The Chinese sturgeon has a habit of upstream migration. It dwells along the coasts of China's eastern areas and migrates back up rivers for propagation upon reaching sexual maturity. It has the longest migration of any sturgeon in the world, and once migrated more than 3,200 km (2,000 mi) up the Yangtze. The sturgeon's reproductive capacity is poor. It may breed three or four times during its life, and a female sturgeon can carry in excess of a million eggs in one cycle, which are released for external fertilisation when mature. The survival rate to hatching is estimated to be less than 1%.」
[ https://en.wikipedia.org/wiki/Chinese_sturgeon 2014-09-11 ]

External source definitions …excluding politically incorrect concepts and other meanings deemed offensive today; may include extended definitions, euphemisms, and mnemonics)
Chinese: sturgeon
Japanese EDRDG: sturgeon
Unihan extended: sturgeon