My fish has turned dark black or has its colour washed out. What is happening?

Colour changes in fish to either very light or very dark coloration indicate that something is wrong, and that the fish is ‘stressed’. This doesn’t mean they need a vacation from work, it means that something is wrong with their environment that is causing them to become ill. If you notice large colour changes in your fish, test your water and look for other signs of disease, and act appropriately.