The Glofish is a genetically modified zebra danio that comes in several different fluorescent neon colors such as red, green, orange, blue and purple. You can now get other species such as tetras as well. They were genetically modified with the purpose to detect environmental pollution. Scientists were able to inject a fluorescent protein gene (from marine organisms) into the zebra danio embryos to create glofish. There are no dyes or color injections into this fish. Successive offspring get the gene passed down to them from parents. They are still working on developing a fish to only fluoresce when in the presence of pollution and a portion of sales goes to the advancement of this research.