Why should I decorate my fish tank?
Decorations are a very important aspect of your aquarium. This is a common question for new aquarium owners. There are two significant reasons to decorate your aquarium.
First, your tank will look better if it is nicely decorated. A well decorated tank can be a very nice accent to almost any room in your home or business. The decorations make the tank more appealing and help the tank work with the other decor in the room. Nice decorating, or aquascaping, can make the tank much more attractive and appealing in itself, and can also enhance the soothing effects that aquariums are known for. Decorations create the atmosphere your fish live in and you look at.
Second, though more important, decorating the tank will make the fish more comfortable. Most fish are well aware that they are prey animals, and as such will be stressed and uncomfortable if they feel exposed and vulnerable. A well decorated tank will increase its inhabitants' feeling of well being, alleviating this stress, thereby improving their immune system and therefore their ability to resist disease and heal. Also, fish in a well decorated tank are more likely to display their natural behavior, show improved coloration, be more active, and spend more time out of hiding! However, this does not mean that nocturnal fish will come out during the day or that fish that normally hide will stay out of hiding.
What should I use to decorate my tank?
The simple answer to this question is, "Decorate your tank with decorations that you like - provided that they are not toxic to the fish." In most cases, the fish don't care if you use a fluorescent-colored castle or a rock with some holes in it - or live plants instead of pearl-colored plastic ones.
To answer this question well, however, it is important to know a little about your fish. Different fish do have different preferences as to what type of decoration, or cover, they have. Fish that are from slow-moving rivers with lush plant growth prefer "soft cover," which is primarily plants, but includes other fine or frilly, generally flexible things. Fish from faster waters or from deep, open areas tend to prefer "hard cover," which is generally rocks, logs, and other large, solid objects.
Just because your fish might prefer one does not preclude the use of the other, it just means that your fish are likely to be more comfortable if more of the cover is closer to their natural environment; and higher comfort means more natural behavior, lower stress, better colors, and better health.
It is important to be aware of potentially toxic decorations. Some minerals are water soluble, and though the stone may not be toxic, when it is dissolved in water it may make a toxic substance or it could reduce the water's ability to carry Oxygen for the fish to breathe. Also, if the stone is soft enough that it could be chewed or rubbed off by the fish, they could choke on it, or it could block their intestines. Also avoid any ceramic items with bright blue, red, or yellow glazes that are not designed for aquarium use - these may contain soluble lead. Non-colorfast inks or dyes could be potentially harmful as they dissolve in the water. Finally, avoid any plastic or rubber items not specifically designed for aquarium use, as these may contain solvents or preservatives that could be harmful to the fish.
Though some people do like to use found items to decorate their fish tanks, I encourage you to only use items purchased at a reputable pet shop as an aquarium decoration to decorate your fish tank.
How should I decorate my tank?
For most fish, 50-75% cover is appropriate. This means that a lot of your tank will be taken up with decorating material, however, this also means that your fish feel that they have never really left their sanctuary, and if the decorations are properly arranged, you will probably be able to better observe even the shiest specimens. Remember, only edges and fringe areas provide good cover; putting a big rock in the tank may fill half of it, but it provides very little cover.
In a freshwater tank, with the exception of a rift lake cichlid tank, or a tank for other particularly hard-water or high pH fish, I recommend that you avoid real shells and coral skeletons, as well as limestone, as these materials will dissolve slowly in the aquarium, increasing the hardness and pH of the water.
Here are some pointers that may be helpful to you:
Remember that the decoration of the tank is largely for the viewer, and decorate to your tastes. Live plants are not the necessity that they were once believed to be, so if you are not interested in providing the care required for these additional inhabitants of your underwater environment, stick to their artificial counterparts. Many very high quality artificial stones, corals, coral skeletons, shells, logs, and plants are available in todays pet industry, so don't feel that you need to use live plants, real rocks, and real logs to have a natural-looking aquarium. On the other hand, many striking, but obviously artificial, decorations are also available if those better suit your tastes.