Pacific foureyed fish
Anableps dowei Gill, 1861
Also calledcuatrojos (spa)
First described in: Gill, T. N. (1861). Description of a new species of the genus Anableps of Gronovius. <em>Proceedings of the Academy of Natural Sciences of Philadelphia.</em> v. 13: 3-6.
Anableps dowii, the Pacific four-eyed fish or the cuatrojos, is a species of four-eyed fish native to the coastal waters on the Pacific side of southern Mexico to Nicaragua. This fish is gregarious and inhabits mangrove swamps, tidal mudflats, and other coastal brackish ecosystems. This species has female biased sexual dimorphism, with males growing to 22 cm (8.7 in) TL while females can grow up to 34 cm (13.4 in) TL. The name "four-eyed fish" comes from how the eyes of the fish are split into two lobes horizontally, each with its own pupil and vision. This allows the fish to see above and below the water at the same time, aiding in predator detection and prey location.
Descriptions from checklists and floras indexed by GBIF
Anableps dowii Gill 1861
Anableps dowii Gill 1861 (Fig. 9I). Pacific Foureyed Fish; Cuatro Ojos Vouchers: UCR 0485-001 (3); other collections: CAS 38460 (2), KU 18686 (1) 18687 (1), 18688 (1) and 18689 (1). Distribution: Central America; from southern Mexico to northern Nicaragua, Pacific drainages; (Nicaragua) Ch, Ne, ER and PN (Pacific); 0–319 masl; Sec, Dia, Amp. Occurrence and conservation status: Nat; LC (2019), population trend unknown. Literature: Villa (1982: 146, as Anableps dowi —misspelled; detailed description, including illustrations and an identification key, and information on distribution and ecology), Carr & Giovannoli (1994: 104, as Anableps dowei —synonym; brief description, including information on distribution and ecology), Robertson & Allen (2015: 2581, as Anableps dowei —misspelled; detailed description, including illustrations, and information on distribution, with a map, and ecology) and Álvarez et al. (2021: e3303; brief description, including an identification key and an illustration, and information on distribution).
Continental fishes of Nicaragua: diversity, distribution and conservation status; with an annotated and illustrated checklist of species and an identification guide to families
From Wikipedia (CC BY-SA), quoted section by section
Description
Anableps dowii has a slender, elongated body with large eyes that protrude from the top of the head. The cornea and irises of the eyes are horizontally divided into 2 differently-sized apertures: the larger, higher lobe is specialized for above-water vision, while the smaller, lower lobe is specialized for vision below water. The fish has specialized muscles enabling each eye to adjust its focus independently, enhancing its ability to adapt to both aerial and aquatic environments.A. dowii has a dark brown body, with a broad, cream-colored stripe runs along the sides and a yellow ventral surface. The species possesses a single, small, posteriorly-positioned dorsal fin with 7-10 rays, large, paddle-like pectoral fins, abdominally-placed pelvic fins, an anal fin specialized into a gonopodium in mature males, and a large, rounded caudal fin. Anableps dowii can be differentiated from the other members of the genus Anableps, A. anableps and A. microlepis, by their Pacific distribution (A. anableps and A. microlepis have Atlantic distributions) and the presence of a cream-colored stripe along the side of the body.
Range & habitat
Anableps dowii ranges as far north as the basin of the Rio Tehuantepec, Oaxaca, Mexico, and as far south as Nicaragua, spanning the countries of Mexico, Guatemala, El Salvador, Honduras, and Nicaragua. The species inhabits waters ranging from inland freshwater canals and tributaries to estuaries and brackish coastal lagoons. Elevationally, the species ranges from sea level (0m) to 670m in Honduras.
What it does
Anableps dowii is insectivorous. During low tide, they will crawl onto shore to eat algae and other organic matter. The species stays at the surface of shallow water (1-5m), with the air-adapted lobe of its eyes staying out of the water, occasionally diving to prevent the upper eyes from desiccation. The species inhabits sparsely vegetated to unvegetated waters, with soft substrate (sand, mud). A. dowii typically inhabits water with a temperature between 24-28 degrees. The species forages at night for insects and invertebrates. The species will jump out of the water in order to catch insects flying above water, which doubles as threat evasion. Jumping is expressed by large, primarily female individuals; smaller individuals may express threat evasion by diving down, away from the water's surface. Anableps dowii engages in schooling behavior. Younger individuals will form schools of 10 to 200 individuals, while larger adults will occur singly or in small groups.
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From the GBIF Backbone Taxonomy and occurrence records (GBIF.org), with Wikipedia and the Source Library. GBIF species 2350681.