Tap water is easy to use for freshwater aquariums, but the chlorine will kill helpful bacteria and your fish. Use an approved kit to remove the chlorine before your fish take up residence.https://kamiworldwide.co.uk/
If you use an under-gravel filtering system, be sure to cover it with about an inch of gravel to aid in filtration. A filter on the side of the tank needs at least two cartridges so that you don’t disrupt the aquatic cycle when replacing one.
Most people use an aquascape in the back of their tank. It is colorful and can remind fish of more tropical surroundings. It also limits the outside stimulation for your fish. Choose something colorful.