I have two small JD's (about 3.5"). One is always very dark, almost black, while the other is always a drab grey. I am not sure of the gender, but can I assume, the grey one will never color up because the dark one is the dominant fish? I only plan on keeping 1, but I got two so I could have a better chance of getting a more colorful fish. I think moving the other one now, while it is still small, will be a lot easier than trying to dump a 7" fish. Thoughts?