You will need to understand the different kinds of fish that live at the three different levels of the tank.
Know the full-grown size of the fish species. If you buy fish that are younger, they will most likely grow in size as they age, so when buying fish, be sure to plan for them to be at their full size to avoid overcrowding. [5] X Research source
With any tank decoration, especially fake plants, beware of sharp or rough edges. This is especially important if any of your fish have long, flowing fins, as these can be easily torn. Silk plants, on the other hand, do not carry the risk of harming the fish. [10] X Research source One great way to determine if something is too rough is to get a cheap pair of nylon stockings. Run these over the edges and points of your decorations in every direction. If they catch or tear the stocking, they are too rough for your fish’s’ delicate fins. Buy several different types of plants for your aquarium in different shapes and sizes. A variety helps to keep the tank interesting to watch and provides different territories for your fish.
Hardy plants that can withstand many conditions are the way to go, especially for beginners. Anacharis grows quickly and can provide food, while crypts can grow into bushes to provide an area for fish to hide and play. [13] X Research source
Boil any structure you plan to put in the tank in water before introducing it to your tank. Boiling will sterilize your wood or rock to make it safe for your aquarium. Boiling wood will kill any bacteria on it and remove tannins that can stain the water.
Avoid having large rocks directly touch the glass. Over time, the rocks may damage the glass, causing stress fractures or cracks. [18] X Research source After boiling rocks, soak them overnight and then brush them to remove loose particles. [19] X Research source
Be very careful when buying decorations with holes or small spaces. While these can be ideal hiding places for smaller fish, larger fish can become stuck and get injured or even die trying to get out. Be sure any hole or archway is significantly larger than your largest fish. If you have young fish, keep in mind their full grown size when picking out such decorations.
Choose a background that fits your theme. An image of a coral reef suggests a natural space. You could go in the other direction with something like a space-themed background if you want a more unique theme. Measure your tank before going to the store, and buy a piece at least 1" longer than your tank to account for uneven edges. When you get home, cut it down to the proper size and tape it to the outside of the back of your aquarium.
