How do you get A guppy blue on insaniquarium?

To get a Blue Guppy in Insaniquarium, you need to first unlock the Guppy type by progressing through the game. Once you have access to the Guppy, you must feed it enough of the appropriate food to ensure it grows and transforms. After feeding it, the Guppy has a chance to evolve into a Blue Guppy. Keep in mind that random factors play a role in the evolution process.