Tropical fish and plants require warmer temperatures, and will probably need to be moved indoors in order to survive. Even in places where the winter is mild, temperatures may drop too low for your plants and fish to thrive. Do some research and invest in a water thermometer so that you can keep track of your water's temperature through the year. If things get too cold for your tropical fish or plants, you'll want to make an environment for them to live inside. This can involve tanks or planters and artificial lighting.
Keep your fish in a warm place indoors where they can't freeze, but not too warm. Things getting too hot may awaken your fish from their torpor, causing their appetites to start back up and requiring feeding throughout the winter. Otherwise, fish will need much less food once the water is less than 50 degrees, and will stop entirely once things are below 40 degrees. Switch to food with less protein as things get cooler, as this is easier for fish to digest.
