The Indo-Pacific genus Solenostomus Lacepède, 1803, belonging to the monogeneric family Solenostomidae, includes at least five valid species: Solenostomus cyanopterus Bleeker, 1854, Solenostomus halimeda Orr, Fritzsche and Randall, 2002, Solenostomus leptosoma Tanaka, 1908, Solenostomus paradoxus (Pallas, 1770), and Solenostomus snuffleupagus Short and Harasti, 2026. Among them, S. cyanopterus, S. leptosoma, and S. paradoxus have previously been recorded from Japanese waters. During a taxonomic study of the genus, four specimens (36.7–57.5 mm standard length) of S. halimeda, collected from the Satsunan Islands (Tanega-shima, Takara-jima, and Okinoerabu-jima islands), Kagoshima Prefecture, Japan, were found in the Kagoshima University Museum Ichthyological Collection. The specimens were characterized by the following combination of characters: first dorsal, pelvic, and caudal fins short; caudal fin rounded, truncate; all fin membranes not incised; olfactory rosette sexually dimorphic, females with a small dorsal patch of nasal lamellae, males with a larger patch filling about half of nasal cavity; premaxillary spine absent in both sexes; and dermal papillae multifid. Although S. halimeda has previously been recorded from the Maldives, Western Australia, Papua New Guinea, Indonesia, the Mariana Islands, the Marshall Islands, and Taiwan, it has not been recorded from Japan. Thus, the presently reported specimens represent the first records of S. halimeda from Japanese waters. In addition, the occurrence of the species in waters off Chiba, Shizuoka, Wakayama, and Kochi prefectures, the Okinawa Islands (Okinawa and Zamami islands), and the Miyako Islands (Shimoji-jima Island) was confirmed on the basis of underwater photographs. The new standard Japanese name “Ginga-furaiuo” is proposed, based on the Okinoerabu-jima specimen. A revised key to the species of Solenostomidae is also provided.

The lumpsucker Eumicrotremus uenoi, previously confused with Eumicrotremus awae, has previously been recorded from the Sea of Japan coast from Yamagata to Hyogo prefectures, Japan, and the southern coast of the Korean Peninsula. Additional records of E. uenoi from Japan include two specimens recently collected from Kumamoto Prefecture, and a single specimen from Shimane Prefecture. A detailed description of these specimens is provided with comments on intraspecific genetic variations. Although the species has been characterized by having three anterior mandibular pores, each with a barbel-like tube, one of the recently collected specimens lacked barbel-like tubes, such being regarded as an intraspecific morphological variation.

A single specimen of Opistognathus (Opistognathidae), collected by biological dredge at a depth of ca. 105 m off Miyako Island (25˚03–04′N, 125˚11–12′E), was identified as Opistognathus erdmanni Smith-Vaniz, 2023, previously known only from the Mergui Islands, in the Andaman Sea off Myanmar (50–55 m depth). The specimen, representing the second record of the species and first from Japan, possessed the following combination of diagnostic features: dorsal-fin rays XI , 11; anal-fin rays II, 10; gill rakers 9 + 22 = 31; predorsal area scaleless; posterior end of upper jaw rigid; 5 dark blotches on dorsum; scales without black spots; dorsal, anal and caudal fins yellowish-white, no white spots on caudal fin; pelvic fin translucent white. The new standard Japanese name “Komorebi-agoamadai” is proposed for O. erdmanni.

The deep-sea whipnose anglerfish family Gigantactinidae includes two genera and 25 species, distributed in the mesopelagic to abyssopelagic zones of the Pacific, Atlantic and Indian oceans. Metamorphosed females of the genus Rhynchactis Regan, 1925 are characterized by absence of frontals, parietals, and maxillae; 0–2 premaxillary teeth (total of both sides 0–4); dentaries toothless or bearing only minute teeth; 2 hypohyals; pelvic bones present; 3 or 4 (rarely 5) dorsal-fin rays; 3 or 4 anal-fin rays; and innermost four rays of caudal-fin branched. The genus includes three species, Rhynchactis leptonema Regan, 1925, R. macrothrix Bertelsen and Pietsch, 1998, and R. microthrix Bertelsen and Pietsch, 1998. Two specimens [NSMT-P 155016 (37.3 mm standard length: SL), and SPMN-PI 51041 (43.6 mm SL)] of R. macrothrix, were collected off the south-east coast of Tanegashima Island and Suruga Bay, Japan, in the northwestern Pacific, in October 2022, and October 2023, respectively. The species is distinguished by the following combination of characteristics: illicium 109–144% SL, with 11–20 long secondary filaments, the five longest 4.1–15% SL (some with bifid tips); length of illicium proximal to emergence of secondary filaments 43–80.5% of total illicial length. The species has previously been recorded from subtropical and tropical waters of the western and central Atlantic, western Indian, and northwestern Pacific oceans from 31˚N to 14˚S, but not from Japanese waters. The above specimens represent the first records of genus Rhynchactis and its species R. macrothrix from the latter region, SPMN-PI 51041, from Suruga Bay (34˚N), being the northernmost record of the species to date. The new standard Japanese names “Shizuku-anko-zoku” and “Shizuku-anko” are proposed for the genus and species respectively.