The functional properties of the outermost retinal circuits involved in color discrimination are not well understood across species. Recent experimental work on zebrafish has elucidated the in-vivo activity of photoreceptors and horizontal cells as a function of the stimulus spectrum, highlighting the appearance of chromatic-opponent signals at the first synaptic connection between cones and horizontal cells. These findings, altogether with the observed lack of gap junctions, suggest that the primary mechanism yielding early color-opponency in zebrafish is a dominant inhibitory feedback. The relevance of the observed neuronal activity is discussed in the context of efficient codification of chromatic information, hypothesizing that opponent chromatic signals provide an optimal codification minimizing signal redundancy. We examine whether these functional properties are general across species by studying the dynamical properties of dichromatic and trichromatic outermost retinal networks. Our findings show that dominant inhibitory feedback mechanisms provide an unambiguous codification of chromatic stimuli, which is not guaranteed in networks with strong excitatory feedback, via gap junctions. This provides a plausible explanation for the absence of gap junctions observed in zebrafish outermost retinal layers. In addition, our model suggests that in zebrafish retinas, the simplest network with dominant inhibitory feedback capable of optimally codifying chromatic information requires at least two successive inhibitory feedback mechanisms. Finally, we contrast the chromatic codification performance of zebrafish-inspired retinal networks with networks having different opsin combinations. We find that optimal combinations might lead to a chromatic codification improvement of only a 13% compared with zebrafish opsins. This suggests that zebrafish retinas are near to optimal codification of environmental chromatic information.