[Histrix]

Anableps anableps (Linnaeus, 1758)

Similar species with identical requirements: Anableps dowi, Anableps microlepis

Common names: Four-eyed fish, cuatro ojos

Class: Osteichthyes
Subclass: Actinopterygii
Order: Cyprinodontiformes
Family: Anablepidae (3 genera, 9 species)
Subfamily: Anablepinae

Ease of keeping: Moderate

Maximum size: 32 cm

Minimum recommended tank size: 45 breeder (prefer tanks with a larger surface area)

Native location: Found in shallow estuarine and coastal habitats of northern South America; Trinidad to the Amazon River delta in Brazil.

Temperature: 24-28º C

pH: variable, neutral – 8.3 all acceptable

Physical description: Distinguishing feature is the horizontally-divided eye, each of which has two pupils and a divided cornea and retina. The lenses are asymmetrical and display different curvatures and thicknesses for the dorsal and ventral portions of the eye. This allows the fish to see quite well both below and above the surface of the water. Elongated body, surface-oriented with superior mouth. Gray base coloration with thin, dark horizontal stripes located on the sides of the body, isocercal tail.

Diet: Anableps anableps is a surface-oriented carnivore. Their wild diet includes insects, miscellaneous invertebrates, and sometimes smaller fishes. Captive diet should include floating foods such as flake and freeze-dried plankton or daphnia. Will also eat frozen meaty items, including worms and brine shrimp.

Gender differences: Males possess a tube-like anal fin called a gonopodium used for internal fertilization.

Breeding: All members of the family Anablepidae are viviparous and give birth to live young. Fertilization is internal and is achieved when the male inserts his gonopodium into the female’s cloaca. There are two mating types, sinistral and dextral.

For successful breeding, feed copious amounts of live and frozen foods.

Aggression: Largescale four-eyes are a schooling fish. They are generally peaceful towards larger tankmates, but will eat any fish small enough to ingest.

Notes:
- Schooling behavior is common with four-eyed fish. Must be kept in groups of at least three, but ideally six or more individuals.
- Four-eyed fish are able to survive out of water and hop about like mudskippers for short periods of time in muddy areas during low tides.
- They can be easily identified from the surface because of their protruding “periscope” eyes. - - - These fish are known jumpers, so keeping the aquarium covered at all times is strongly recommended.
- The addition of a full spectrum incandecent lamp on one side of the tank has proven to be of benifit to them. They do like to bask underneath it and I have had better rates of live birth in females that have access to this over those that did not.

References:
• Moyle, Peter B. & Cech, Joseph J. Fishes: An Introduction to Ichthyology, 5th Edition. Upper Saddle River, NJ: Prentice Hall, 2004.
• Paxton, John R. & Eschmeyer, William M. Encyclopedia of Fishes. San Francisco, CA: Fog City Press, 2003.

Links to other webpages:
• http://fish.mongabay.com/species/Anableps_anableps.html, Four-eyes I Anableps anableps
• http://ebiomedia.com/gall/eyes/4eye.html, Anableps: Seeing above and below water at the same time
• http://www.jjphoto.dk/fish_archive/aquariu...ps_anableps.htm, Anableps anableps
http://filaman.ifm-geomar.de/Summary/Famil...mary.cfm?ID=214, Family Anablepidae

[attachmentid=18158]
Artwork scanned from Paxton, John R. & Eschmeyer, William M. Encyclopedia of Fishes. San Francisco, CA: Fog City Press, 2003.

Photos below taken by K. Birkett.
[attachmentid=17778]
[attachmentid=17779]

Attached File(s)

•  4eyes1.jpg (65.08K)
  Number of downloads: 42
•  4eyes2.jpg (64.6K)
  Number of downloads: 36
•  four_eyes.jpg (12.59K)
  Number of downloads: 38

This post has been edited by Histrix: 06 July 2006 - 08:35 AM