Most of these in my area are black or brown, some are olive and a few are orange. I've seen one that was maple-leaf red. I went back to the area, couldn't find the red type, so I collected the orangest of the orange, and will try to isolate this 'red' expression. I have about seven specimens. Is there anything different about slug genes than fish genes? Should I force the reddest individuals to self-fertilize and cross the reddest offspring of these self-fertilized batches, or let them cross at will and just remove the darker offspring? What about crossing back the offspring with the parents?