betta fish
Fish Herder
He is a marble! that colour change is definitely not a sign of illness
he is very pretty too, I had a young marble that was constantly changing colour as a youngster so it seems odd your fish has started doing this now, how long have you had him again? where did you get him from? it may just be he has changed colour many times before you got him and had a rest before changing again? they are all different though so there is no telling what they may do! as for dechlorinating new tap water it is good practice that you do depending on the area you live in some water boards add more chlorine to their water and other nasty stuff that is toxic to fish, dechlorinating water does not do the fish any harm where as not dechlorinating may, it really depends how much is present in your water source and without that information I will always dechlorinate, Prime is the best a little amount goes a long way.