TOKYO, April 25 (Reuters) - The Canadian dollar fell 0.4 percent in early Asian trade on Tuesday after U.S. Commerce Secretary Wilbur Ross said his agency will impose new anti-subsidy duties averaging 20 percent on Canadian softwood lumber imports. Canadian dollar fell to as low as C$1.3555 per U.S. dollar CAD=D4 , its lowest level since late December, edging near its December trough of C$1.3598 to the dollar.