This phrase basically means, “something’s better than nothing,” rather loosely illustrated here in a drawing by Arvid Torres (you should have been happy with the shrimp). It can be used to refer to someone’s partner too, as in, “he really scraped the bottom of the barrel with that one,” as used in Taiwanese author Li Ang’s latest novel, to portray the racist and misogynist tendencies of Taiwanese men in the anti-government pro-democracy protests of the 1980s:
(As no normal women [Lin Hui-shu is the product of a mixed marriage between a mainland soldier and an aboriginal woman] dared to be associated with Chen Ying-jun, he really didn’t have much choice, and as, Lin Hui-shu was really quite attractive, the two quickly entered into a relationship.)
雖然偶有政治犯同學戲稱他無魚蝦也好，但多半是羨慕又帶嫉妒。 (Although some of his political prisoner comrades joked with him that he was really scraping the bottom of the barrel, most admired him with a little bit of jealousy mixed in.)
You’ll note that she uses it directly as an adjective here, Subject + adjectival phrase.
This phrase also works in Mandarin – hurrah!