When setting up a marine tank, care must be taken not only to create the desired visual effect but also to consider the varied needs of the marine species you wish to keep. Once the substrate has been prepared, the next step is to arrange tank decor, taking great care to ensure that it is clean and firmly supported in the aquarium. If necessary, pieces can be held together with silicone sealant, to make them more secure. Arrange the rockwork to contain niches and crevices for the fish to use as retreats. Position rockwork toward the back of the aquarium, leaving a clear swimming area at the front—this will make the fish and other marine life more visible. Live rock should only be added once the tank is full and the water conditions have stabilized. Heating and filtration components can then be fitted around the rocks. When making your arrangement, be careful not to create “dead spots”—areas where current from the filter does not reach—because uneaten food and debris can accumulate here, which will lead to a gradual deterioration in water quality.