Growth of the visual system in the African cichlid fish, Haplochromis burtoni. Optics.

We have measured the chromatic aberration and optical resolution of the lens of the African cichlid fish, Haplochromis burtoni as a function of growth. We found that in H. burtoni, lenses of all sizes have a longitudinal chromatic aberration of ca 1.9% of the focal length. The resolution of the lens increases as the lens grows larger, presumably because diffraction effects decrease and any imperfections in the lens become relatively less significant. We found the lens in H. burtoni is very nearly diffraction limited so that a small lens (0.59 mm) has a resolution of 289 sec of arc and a large lens (2.90 mm) has a resolution of 66 sec of arc in red light (604 nm). This resolution is nearly ten times greater than can be resolved by the cone matrix.