I purchased 4 dats all about 5" about 2 weeks ago; they came nice with the strip really bold and thier gold color shimmering, but after 1 week they turn gray and no stripes and hidding sideways under a HUGE piece of Driftwood I have in the tank..I was wondering if this is normal how long does this last or is this thier nature! by the way they eat krill..water is a little soft PH 6.4..