Big brother, is this fish really tasty? It looks like a black sea bream that fell into a life of crime and ended up on the most-wanted list!
Literal
Big-brother, this honorable-fish really delicious [question-の]? Black-sea-bream [subj-が] yakuza [to-に] fell, nationwide wanted-[passive-された] like honorable-fish [copula-だよ]?
極道に落ちて 'fell into the yakuza life' is a vivid metaphor applied to a fish — 極道 means 'gangster/yakuza' and 落ちる 'to fall into.' 全国指名手配 'nationwide wanted/search warrant' is a police compound. The humor comes from describing a fish's appearance in criminal terms. A creative, playful child-speech moment.