Four-eyed fish
Four eye ( Anableps anableps )
The Four Eyes ( Anableps ) are a genus of about 30 cm long viviparous carp, which are common and on the Pacific coast of Central America in muddy coastal waters of northern South America ( Venezuela and Trinidad to the Amazon estuary ).
Anatomy of the eye
Four eyes are surface fish, which a transverse septum the eye with one pupil is divided into two halves, so that the animals can see the same above and below water. The upper half of the lens is weak, the lower greatly curved so as to each provide for the correct refraction of light. It is the only known vertebrates (along with a frog ) that can be seen simultaneously sharply above and below water. To be able to see both above and below the water, there are in the retina of the eyes of this fish over ten opsin types (compared to man has only four).
Species
- Anableps anableps
- Anableps dowei
- Anableps microlepis
Care in the aquarium
Some specialized aquarists four eye is maintained in brackish water aquarium. They are considered possible in a tank with low water levels and a well-fitting cover to above the water surface humidity is high. The surface in the warm aquarium fish needs a beach area on which the fish can rest and an open swimming area. They are kept in groups of six to eight animals, so that couples can form.