Thread:LeoYuHD/@comment-177.86.94.65-20181012233438/@comment-32671756-20181016040352

From what I can remember, the Gangly Gompler is one of several quest-related fish, requested by the Sea Fisher after you have finished all his five quests and received the quest named "More Fish In The Sea".

He will request for one of these several fish and tell you how and where to fish them. Only after that can you have a chance to catch the required fish. The Sea Fisher will randomly choose the type of the fish, and will ask for another one after you have turned in the said fish for his reward. It is suggested that you store several quest fish in some chests and save them for future use.

for more info, check Fisherman_Quest_Fish.