I recently did a little research project on Melanotaenia australis, the Western Rainbowfish, to determine if they had a preference when it comes to the color of medium they lay eggs in. I gave the fish 5 different colored mops and counted eggs daily from the mops. Overall, I sampled over 3,000 eggs in 14 days from 4 trios. A little tip for breeding them, green colored mops were their favorite, and they laid a significant majority of eggs in that color. I hopefully will have this research published in a journal soon.
The Western Rainbow is a very peaceful and easy species to keep. They only get about 4 inches and are active and fun to watch. They are jumpers, so it is important to cover the tank. They make great dither fish for cichlids.