Whereas Tempel & Himstedt (1979. Color vision in salamander larvae. Z. Naturforsch., Sect. C, 34[9/10]: 890–891), based on the presence of only blue-yellow opponent-color ganglion cells, concluded that the vision of fire salamander larvae was dichromatic, a newer study by Przyrembel et al. (1995. Trichromatic color vision in the salamander [Salamandra salamandra]. J. Comp. Physiol., A, 176[4]: 575–586) claimed that adults of the same species actually had a trichromatic vision, as they were able to discriminate blue from green, and green from red in laboratory experiments. However, a good vision may not be a prerequisite of successful hunting, as revealed by an article by Michael Lannoo (1986. Vision is not necessary for size-selective zooplanktivory in aquatic salamanders. Can. J. Zool., 64[5]: 1071–1075), who tested nocturnally active larvae of the North American spotted salamander, Ambystoma maculatum.

There's a useful little review in the Jehle et al 2011 book, pp56-58, with references therein.