gracilis, Capoeta Temminck [C. J.] & Schlegel [H.] 1846:201, Pl. 100 (figs. 2, 2a-b) [Fauna Japonica Parts 10-14; ref. 4374] Streams near Nagasaki, Japan. Holotype (unique): RMNH 2499. Type catalog: Boeseman 1947:157 [ref. 12876]. Subjectively invalid; secondarily preoccupied by Barbus gracilis Jerdon 1849 when Günther 1868 placed gracilis Temminck & Schlegel in Barbus. Replaced by and objective synonym of Barbus homozonus Günther 1868; the name homozonus should be used for this species unless gracilis is treated as a nomen protectum. •Valid as Gnathopogon gracilis (Temminck & Schlegel 1846) -- (Okada 1961:436 [ref. 6363]). •Valid as Squalidus gracilis (Temminck & Schlegel 1846), subspecies gracilis -- (Kawanabe & Mizuno 1989:321 [ref. 25598], Sato 1995:51 [ref. 25531], Nakabo 2000:271 [ref. 25086], Matsuura et al. 2000:126 [ref. 26000], Nakabo 2002:271 [ref. 26001], Miuchi & Kunimatsu 2021:18 [ref. 38479], Saiki et al. 2023:69 [ref. 40766]). •Valid as Squalidus gracilis (Temminck & Schlegel 1846) -- (Sawada in Masuda et al. 1984:56 [ref. 6441], Hosoya & Jeon 1984:41 [ref. 17431], Okamura & Machida 1987:104 [ref. 22279], Kim 1997:211 [ref. 24032], Watanabe 1998:263 [ref. 23491], Sato et al. 1998:36 [ref. 24972]). 2°Homonym. Current status: Valid as Squalidus gracilis (Temminck & Schlegel 1846). Gobionidae. Distribution: East Asia: Japan. Habitat: freshwater.