Experienced designer Achievement
Spend 10,000 coins decorating your aquarium
This is a cumulative total of all decorations purchased for your aquarium. You'll be spending far in excess of 10,000 coins to fully upgrade five tanks for the "Perfect aquarium" achievement, so refer to it for more details on decorating your aquarium. This achievement will unlock very early in your time with this game, definitely by the time you reach level 12-15 or so.