So I finally found a Golden Tonga Blenny (at Vivid Aquariums) and it was fairly golden/yellow in the store (not bright yellow) and when I added him to my tank it turned to a brownish/blackish color. Is this normal? Will its color improve and go back to golden/yellow? At the store I asked about its color, and they said that they can change color. Just wanted to see if anyone had any feedback. Thanks!