The answer lies in the fact that at one time there were different terms for the way one carved each type of fish that might be presented at the table.
According to The Accomplished Lady’s Delight (1719) one addressed oneself to various fish as follows –
Barb a Lobster
Chine a Salmon
Culpon a Trout
Fin a Chevin
Scull a Tench
Side a Haddock
Splat a Pike (though who would want to eat a Pike I cannot imagine!)
Splay a Bream
String a Lamprey
Tame a Crab
Tranch a Sturgeon
Transon an Eel
Tusk a Barbel
Gobbeting – another way to treat the Trout appeared later – probably in the early 19th century along with Frushing a Chub.
A trout that has been culponned or gobbeted – photo by kind permission of Victoria of Mission Food from The Adventures of Cletusthe Trout.
I think that’s enough useless new words for a day or two…