By Robert Frost?
(Tsuriotoshia sakana wa ookii; “The fish that got away is big”)
The things that you lost your chance at, or failed to get, seem all the more appealing because of the pain of missing out. The fish that you nearly caught but let slip feels like it was especially large and desirable. A sort of “the grass is always greener.” The opposite of “sour grapes.”
We begin toward the end, with the topic-marker particle は (wa). The noun marked as the topic of discussion is 魚 (sakana), “fish.” What kind of fish is specified by a compound verb: 釣る (tsuru), “to fish,” in conjunctive form and coupled with 落とす (otosu), “to drop” or “to lose,” in past tense, which allows it to attach to and modify a noun. And finally, the comment on this fish-that-was-fished-up-and-then-dropped takes the form of a single adjective in conclusive form: 大きい (ookii), “big.”
Contrast this with the English-language expression about the fish that got away being magnified by lies on the fisher’s part, either to inflate their own prowess (at nearly having landed something truly impressive) or hide their faults (at having allowed an ordinary catch to escape).
Some versions replace the compound verb with 逃した (nogashita), “let escape.” The character 魚 can also be read as uo without any change in meaning. There are a number of synonymous phrases as well; two of them specify catfish or eel as the lost catch, while especially tragic ones extol the wisdom or beauty of lost children.
(Tsuriotoshita sakana wa ookii to iu kyoufu ni tsukekonde, ima shika nai you na toushi kikai to misekaketa sagi ga sono toki hayatteimashita.)
[There was a scam popular at the time that took advantage of people’s fear that the chances they missed were the best ones by dressing itself up as a now-or-never investment opportunity.]