The family Cichlidae contains approximately 2000 species that live in diverse freshwater habitats including murky lakes, turbid rivers, and clear lakes from both the Old and New Worlds. Their visual systems are similarly diverse and have evolved specific sensitivities that differ along several axes of variation. Variation in cornea and lens transmission affect which wavelengths reach the retina. Variation in photoreceptor number and distribution affect brightness sensitivity, spectral sensitivity and resolution. Probably their most dynamic characteristic is the variation in visual pigment peak sensitivities. Visual pigments can be altered through changes in chromophore, opsin sequence and opsin expression. Opsin expression varies by altering which of the seven available cone opsins in their genomes are turned on. These opsins can even be coexpressed to produce seemingly infinitely tunable cone sensitivities. Both chromophore and opsin expression can vary on either rapid (hours or days), slower (seasonal or ontogenetic) or evolutionary timescales. Such visual system shifts have enabled cichlids to adapt to different habitats and foraging styles. Through both short term plasticity and longer evolutionary adaptations, cichlids have proven to be ecologically successful and an excellent model for studying organismal adaptation.

家庭丽鱼科包含大约 2000 种生活在不同淡水栖息地的物种，包括来自旧世界和新世界的浑浊的湖泊、浑浊的河流和清澈的湖泊。他们的视觉系统也同样多样化，并且进化出了特定的敏感性，这些敏感性在几个变化轴上有所不同。角膜和晶状体透射率的变化会影响到达视网膜的波长。光感受器数量和分布的变化会影响亮度灵敏度、光谱灵敏度和分辨率。可能它们最动态的特征是视觉色素峰敏感性的变化。可以通过生色团、视蛋白序列和视蛋白表达的变化来改变视觉色素。视蛋白表达通过改变其基因组中七个可用视锥视蛋白中的哪一个被打开而变化。这些视蛋白甚至可以共表达以产生看似无限可调的视锥灵敏度。生色团和视蛋白的表达都可以在快速（数小时或数天）、较慢（季节性或个体发育）或进化时间尺度上变化。这种视觉系统的变化使慈鲷能够适应不同的栖息地和觅食方式。通过短期可塑性和长期进化适应，慈鲷已被证明在生态上是成功的，并且是研究生物体适应的极好模型。