Journal of Fish Biology (2013) 82, 1011–1031 doi:10.1111/jfb.12051, available online at wileyonlinelibrary.com Feeding ecology of two lanternfishes Diaphus garmani and Diaphus chrysorhynchus H. Tanaka*†, C. Sassa*, S. Ohshimo* and I. Aoki‡ *Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira, Nagasaki 851-2213, Japan and ‡Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-8657, Japan (Received 4 May 2012, Accepted 15 December 2012) The feeding ecology of two dominant lanternfishes Diaphus garmani and Diaphus chrysorhynchus was studied in the continental slope region of the East China Sea, off western Kyushu (31–33 ◦ N; 128–130 ◦ E). Stomach contents of D. garmani were composed mainly of crustacean zooplankton, such as copepods, euphausiids, decapod larvae and amphipods, and also of appendicularians. Stom- ach contents of D. chrysorhynchus were composed mainly of crustacean zooplankton, cephalopods and fishes. Diel changes in stomach fullness indicated that D. garmani fed more actively at night than in the day. On the other hand, although feeding activity of D. chrysorhynchus did not change drastically between day and night, it tended to feed on large prey items in the benthopelagic zone during the day and on zooplankton in the epipelagic zone at night. Daily rations of food were estimated to be 2·54% of body dry mass for D. garmani , and 2·38% of body dry mass for D. chrysorhynchus .  2013 The Authors Journal of Fish Biology  2013 The Fisheries Society of the British Isles Key words: continental slope; daily ration; diel vertical migration; diet; East China Sea; Myctophidae. INTRODUCTION Lanternfishes (family Myctophidae) are the dominant mesopelagic fishes in most oceanic ecosystems. Because of their large biomass and the trophic link between zooplankton and higher trophic levels, myctophids play a key role in the oceanic food web (Gjøsaeter & Kawaguchi, 1980; Brodeur & Yamamura, 2005). The East China Sea (ECS) supports important fishing grounds for both pelagic and demersal fishes (Yamada et al ., 2007). Myctophids are abundant both on the con- tinental shelf and on the continental slope of the ECS. Recent studies have shown that Garman’s lanternfish Diaphus garmani Gilbert 1906 and golden-nosed lantern- fish Diaphus chrysorhynchus Gilbert & Cramer 1897 are abundant and dominant myctophids on the continental slope of the ECS, off western Kyushu (Ohshimo, 2004; Ohshimo et al ., 2012), whereas skinnycheek lanternfish Benthosema pterotum †Author to whom correspondence should be addressed at present address. Hokkaido National Fisheries Research Institute, Fisheries Research Agency, 116 Katsurakoi, Kushiro, Hokkaido 085-0802, Japan. Tel.: +81 154 91 9136; email: tanakahs@affrc.go.jp 1011  2013 The Authors Journal of Fish Biology  2013 The Fisheries Society of the British Isles