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Decorating Your Aquarium

Things to Consider if You Use Things You Find as Aquarium Decorations

(The First Tank Guide)

Why Should I Be Concerned About what I Decorate My Aquarium With?

There are several things to be concerned about with any item or decoration you put in your aquarium, or any piece of equipment you use with your aquarium. Generally these all boil down to is this thing going to hurt my fish? Generally, if you are purchasing your decoration or equipment from a reputable pet shop as an aquarium decoration or piece of aquarium equipment, everything can be assumed to be aquarium safe.

However, there are still issues to keep in mind, such as not using sea shells or coral skeletons in freshwater aquariums because they can cause problems with chemistry (see 4 and 6 below). Of course, at a good pet shop, someone would be likely to point this out to you before you made the purchase...

Here are the seven primary concerns you should have when considering items to use as aquarium decorations:

  1. Is the item aquarium safe? Will it dissolve in water or release toxins into the water, or react with some of your chemicals or additives to produce a toxin. If you understand what could cause a problem like this, and what might react with your chemicals, and what the items you are choosing are composed of, then this is not an issue, otherwise, this could be a cause of problems. Remember, many plastics can release potentially toxic chemicals when submerged in water for long periods of time.
  2. Is the item you are collecting clean? Has it been exposed to some kind of waste, such as petroleum, cleansers, detergents, perfumes, or other potential toxins or irritants that could be dangerous to your fish? If it has, do you have a reasonable means of safely removing this from the item - and of telling whether it is there in the first place? If not, you should not use the items in your aquarium.
  3. Is it possible for the item, or a piece of the item, to be consumed by fish? Can your fish eat or bite off pieces? Is this a problem? Many fish will bite or chew on things, however, biting off a piece of a soft rock may be fatal, or may release a toxin that was previously secured inside the rock, or may expose a layer of something water soluble that could dissolve in the water and cause problems. Chewing on wood can be good for some fish, but some plant matter can be harmful to some fish. You should be familiar with these issues before collecting items for use in your fish tank.
  4. Is the item going to decompose or degrade in water? If the item becomes soft or begins to fall apart when it is in water for a prolonged period, this can cause problems with chemistry (see below) or with the aquarium safety of the item or possible consumption issues (see above).
  5. Is the item bearing some kind of pathogen or parasite? Baking, boiling, or in some cases, exposing to ultra-violet light can often eliminate pathogen risks, and this is probably the easiest to deal with (and the most commonly thought of) concern with using found items in your fish tank.
  6. Is the item going to cause chemical changes in the water? Some items, such as sea shells, limestone, coral skeletons, and wood can cause changes in pH or hardness, or can cause other issues with water chemistry. These can cause problems for your fish, or difficulty in maintaining the tank.
  7. Is the item going to be sharp or abrasive? This is not only an issue with found or collected items, but also with items you purchase from a shop. If fish run into items with sharp corners or edges, or items that have a rough surface, it is likely that a fish will get injured. The flightiness of the fish you are getting, the size of the tank, the number of other hiding places, the size of the 'rough' item in question (particularly when compared to the tank as an environment and the fish in question), the number potential 'fright' factors in the environment around the tank, and other factors contribute to the risk with an object like this.

If I Have Something and Want to Use It in My Aquarium, How Do I Clean It?

If there are any chemical issues, hardness issues, consumption issues, or exposure to toxins (as noted above) with the item, you will need to not use the item in your aquarium.

However, if the item is known to otherwise be aquarium safe, you can clean it for use in your aquarium.

First, I would recommend washing the item thoroughly in cool running tap water. You will probably want to take a stiff bristled brush (which has not been used with household cleansers or other dangerous chemicals) and scrub down the item to make sure you have removed anything that can be removed - this may also expose that the item was softer or more fragile than you expected, and therefore inappropriate for an aquarium decoration. Remember, if a stiff bristled brush can damage the surface of the item you are cleaning, then a fish can probably damage it as well - and it may become even softer after being under water for a few days or weeks...

Once you have cleaned the item, you will want to sterilize it. The two easiest ways to do this are to boil the item or bake the item. Either way, you want to get the item to a core temperature above 200°F for at least ten minutes, though longer is better. This should kill anything living on or in the item that could survive in your fish tank. Again, this may warp, damage, or change the item you are trying to sterilize. If this does alter the item, then the item probably was not safe for use in your aquarium to begin with.

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March 12, 2003
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