Last semester, in Waves and Optics, we discussed Rayleigh scattering. I described some simple examples, including the famous blue sky, and orange sunset. Earlier in the semester, I had coincidentally noticed that Squirt soda in a clear glass tends to be a little blue in hue, and not surprisingly, looks orange if held in front of a white light. So it turns out that in addition to milk drops in water, Squirt soda also exhibits this effect.
Later in the semester, one of the students brought in a bottle of squirt to test my suggestion and did the demo for the whole class. After a little tinkering, it works best cut in half with water. This is for a large glass, so if you want to use a fishbowl or tank, you may have to dilute it even further.