Research has shown that adult zebrafish have a
complex visual system, with two possible opponent mechanisms.
Anatomically, zebrafish retina develops in a sequential
manner and is immature at hatching. The purpose of the
present study was to assess zebrafish retinal development
using the electroretinogram (ERG). ERG responses to visual
stimuli were obtained from 4–5, 6–8, 13–15,
and 21–24 days postfertilization (dpf) zebrafish.
Individual waveforms were assessed and compared across
the four age groups. Spectral-sensitivity functions were
calculated for the a- and b-wave components
of the ERG response. Results showed that the ERG waveforms
and spectral-sensitivity functions varied with age. While
the 21–24 dpf subjects had an ERG waveform that was
similar to that of adults, the younger subjects did not.
Although there were modest differences in the a-wave
spectral sensitivity, substantial differences were found
in the b-wave spectral sensitivities across the
ages. There was a consistent strong response to ultraviolet
wavelengths, while across the remaining parts of the spectrum,
there was a gradual increase in sensitivity with age. Also,
the 21–24 dpf subjects appear to have adult-like
U- and S-cone functions, but were missing the L-M and the
M-S opponent mechanisms found in the adult. These results
support the findings of the anatomical studies and demonstrate
that the zebrafish is a useful model for examining the
development of retinal function.