The main thing that you need to decide when choosing a custom aquarium is whether you are going to keep freshwater or marine fish in it. While there are many factors that are important for setting up your fish tank, water quality is perhaps the most important of all. Freshwater fish are generally immersed in water coming from the domestic supply. Fish in the tank would have started the acclimatizing process in the dealer`s tanks. Most of these fishes adapt quite easily with the exception of some specialized species that are more sensitive to the makeup of the water. The ph of the water is generally tested to determine if it is acidic or alkaline. The DH is also checked to see if the water is hard or soft. It is best to use a custom kit to get the right type of water for your fish particularly when you are a novice. In addition to the quality of water, you also need to get the lighting right in custom aquariums. Light allows you to see into the tank to check if everything is ok. It also stimulates the fish into activity and allows other living species to thrive. Custom aquariums generally have inbuilt heaters. If you have a number of tanks and store them in the same space it might be cheaper to heat the entire room than each individual aquarium.