Join Date: Jun 2010
Location: Jakarta, Indonesia
If I'm not mistaken, galaxy is from metallic/dragon line but with incomplete genes that make up those traits. It shows dots of metallic scales. The background color isn't important - whether koi, fancy, or simple multi. As long as it shows specks of metallic scales on all or most of its body, it is considered a galaxy.
Not sure if it is influenced by marble genes, but most I see are associated with marble.
Any how, galaxy is just another fancy commercial name. Being marble and incomplete metallic genes, it might go through color changes and
shouldn't breed true.