[Ebook] 500 freshwater aquarium fish – Livebeavers – Four-eyed Fish (Anableps anableps)
This species’ common name is derived from the two pigmented horizontal flaps of tissue that extend across the eye to meet (but not fuse) in the center of the pupil, effectively dividing the eye into an upper and a lower portion. Modifications to the eye lens allow Anableps to see above and below the water simultaneously. This ability is enhanced by a split retina: one part receives the incoming light rays from above the water, while the other receives those that originate underwater. The Four-eyed Fish is an interesting but large and somewhat challenging species. Two other species with similar characteristics, size, and requirements are also occasionally available: A. dowei (Pacific Four-eyed Fish) from Mexico to Nicaragua; and A. microlepis (Fine-scaled Four-eyed Fish) from the Orinoco delta to the Amazon delta.
