Breeding Four-Eyed Fish (Anableps Anableps) In The Aquarium

Four-Eyed Fish, Largescale Foureyes, Common Four-Eyed Fish

Distribution

This is a brackish water species that naturally inhabits the coastal areas of mangrove forests stretching along the northeastern coast of South America: from the Gulf of Paria (between the coasts of Venezuela and Trinidad and Tobago), through the delta of the Amazon to the delta of the Parnaíba River in the Brazilian state of Piauí. These waters are primarily characterized by fairly large daily fluctuations in level due to tidal flows. The four-eyed fish has adapted to life in these difficult conditions by migrating constantly between areas with permanent water (where it stays during low tides) and areas flooded during high tides.

Appearance

This species has an elongated body that slightly narrows around the tail fin. Its distinguishing feature is the unusual structure of the eye, which is horizontally divided by a dark band of epithelial tissue. In this way, the fish has two corneas, two pupils, a single elliptical lens, and one retina divided into two sections. The asymmetrical lens is flattened on the top like a human's, and curved on the bottom like other fish. This structure allows the four-eyed fish to see at the same time what is happening above and under the water. The fish's color is beige-gray with a lighter belly and several dark, narrow stripes along the body's sides. The species also has a pale, light stripe on its back, which splits at the head and narrows towards the tail. The female is larger than the male. The male has a gonopodium, and the female's sexual opening is covered by a movable fold of skin.

Behaviour

This is a schooling fish that should be kept in a group of several individuals. Given the specific environment it lives in, it is best kept in a species tank. If we decide on a community tank, we should avoid aggressive and very energetic species. We can try to introduce a group of Indian glassfish or yellow tangs, or even a mudskipper. It's a peaceful species, active, may be shy and nervous in too small a group, in too cramped an aquarium. Females can be somewhat aggressive during pregnancy. The fish swim on the surface of the water, only diving when they are frightened or lack food. In nature, fish feed twice a day (during the tides), their diet consists of: land insects, crabs, smaller fish, snails, mussels, and also algae (mainly diatoms and red algae). The fish take food from the surface of the water or land.

Aquarium

The four-eyed fish requires a truly large tank - much longer than it is tall (the required tank length is a minimum of 120 cm). The water level within should not exceed 20-25 cm. The décor should resemble natural conditions as much as possible. Therefore, a thin layer of sand is spread on the bottom, leaving about 1/3 of its surface completely empty. Tangled roots and branches sticking out of the water, imitating mangrove forests, and flat stones sticking out of the water or specially piled up from sand dry places are necessary (the fish like to rest on such a surface, jumping out of the water). Required fairly strong lighting, an efficient filter (the species produces a lot of waste), regular partial water changes, a tight cover on the aquarium, and warm, humid air above the water surface (the four-eyed fish is an excellent jumper). The water should be salted to a level of 1.005-1.010 kg/l (i.e., 12-16 to 17-22 g of sea salt per liter of water).

Reproduction

This species is viviparous. Breeding this species is not an easy task. The first obstacle may be the natural anatomical structure of the male sex organs - the male's gonopodium can only protrude on one side, while the female's genital opening is also located on a specific side - right or left (this is an individual issue). This means that in our group of females and males, we may not have a matching pair. The second factor is the premature birth of fry, which may be caused by the female's inexperience, stress, poor water quality, inadequate diet - it is not entirely clear. Therefore, a pregnant female is best isolated and fed both live and vegetable food (her appetite during pregnancy significantly increases). Pregnancy lasts 12 weeks (this period depends on the water temperature), and after this period the female gives birth to a fully formed, quite large (2-3 cm) fry - up to 10 young. The parents do not eat the fry.