The following are instructions on the set up of an aquarium. The information is based on ten years of experience raising and caring for tropical fish.
Placing your tank
The first step is to choose an area for your tank that's comfortable for you and not in a place where it will have to be moved, or will be bumped or leaned against. Each time you move your aquarium you change the way the tank is set, if only a little, and this puts stress on your fish. Also avoid placing your tank in areas where, it will be exposed to cold air or drafts and extreme heat such as; near doors, air conditioners, radiators, and air vents. The cold could cause your heater to work extra hard and the heat can make the water too warm for your fish.
Cleaning your tank
Cleaning your tank is very important, weather you have a new or used tank cleaning is still very necessary. To clean I recommend using a chlorine bleach and water solution ( Do Not Use Soap). Use a sponge to apply the solution, clean the inside as well as the outside, and if needed use a hard bristle brush to clean stains and spots. Be sure to triple rinse your tank to remove all residue, even a small amount of chemicals can affect the health of your fish.
Decorations and gravel
Decorations are a major part of what makes an aquarium fun. First choose a background that is not too busy, it's been my experience that busy backgrounds can cause your fish to be shy and not swim around, I recommend a background of plants and fish, or a solid color. The next step is the gravel which is the "soil" of your aquarium. I prefer to use the fine or medium grain gravel, and the color should be one that enhances the color of your fish (red piranhas respond to colors like black and orange). Always clean gravel before spreading it inside your tank, even new gravel that looks clean can be full of dust and dirt. Pouring the gravel in is only the start, when spreading your gravel its best, especially when using live plants, to have an upward slope from front to back. Usually about 1-2 inches in the front and 3-5 inches in the rear, this will aid in cleaning. If you have live plants when they grow the old parts break off and fall to the bottom also the fish waste collects there, this waste is called detritus. The slope along with the water movement brings the detritus to the front of the tank where it can be removed easier with a siphon. Other decorations such as plants, rocks and tree roots should be moderate, decorations should enhance not clutter. Place decorations so your fish have some privacy but allow swimming space. (For breeding piranhas there should be room for the breeding pair to circle each other "see breeding page"). Choosing between live and plastic plants is a choice of how much time you have to devote to the aquarium, live plants require some maintenance. I do recommend, if you use live plants, that you get them from a pet store , plants collected from rivers and streams can introduce disease and parasites to the aquarium. Also if you use rocks and tree roots from lakes or rivers you should scrub them with a chlorine and water solution to remove anything clinging to the object. Decorations should be spread out and placed toward the rear leaving the front for swimming.
Filling the tank
The final step is filling your tank with water. The method I use so as not to the decorations just set up is to use a small bowl. Place the bowl in the center of the tank, resting on the gravel. Pour the water slowly into the bowl , allow the water to flow over the sides of the bowl , this creates an even flow of water instead of splashing which would scatter the gravel and undo all your hard work. Fill the tank 1-2 inches from the top, this allows for the displacement of water when removing the bowl, adjusting objects, and adding equipment. Now that your tank is decorated and filled with water it's time to set up your pump, filter, lights, and heater. All of these items use electricity to operate so be careful and read and follow the manufactures instructions. After the tank and equipment is set up and operating the aquarium should be allowed to set empty for 48 hours to allow chlorine and other gasses to evaporate before adding your fish.