Green shad looks pretty straightforward using a twinjector. Top looks like a very dark watermelon green, bottom looks like chartreuse being affected by the top color. Could be green chartreuse as well.
The motor oil shad pic is bright, either slightly over exposed or too much glare. Maybe just the white background, but it's hard to tell if the bottom is yellow or chartreuse. I would try chartreuse first, maybe darken with just a touch of motor oil in it. (really, just dip a toothpick in the colorant, you'd want less than a drop I think) Personally, I like this color but I'd probably hit it with some black flake.
Hmm, don't have a twinjector, might have to try hand pouring some 7" rtw laminates.