Once we arrived at 東港 Donggang from 小琉球 Xiao Liu Qiu Island, we went to explore the 東港華橋市場 Donggang Seafood Market. While we had read online that the Donggang Seafood Market was closed on Fridays, at least half the stalls were opened when we were there, including some stalls selling raw chicken and fish.
There were plenty of stalls selling sashimi and seafood, so we picked one that appeared to slice their fish only upon orders. The sashimi was fresh, and we particularly enjoyed the toro and swordfish. The normal tuna was not bad too. We have had better salmon before, and would recommend that instead of ordering the generic Moriawase Mixed Platter (we paid NT500 for our platter), just pick the fish marked as signature, or the seasonal specials.