Using Wood in Aquarium with Tropical Fish

Questions regarding using wood in aquariums are brought up from time to time via the news groups and the mail lists. For the past couple of years we have been reading the questions and the responses with great interest.

Wood offers a unique structure for decorative uses in aquascaping your aquarium. It offers a dimensional design element that is hard to duplicate. But it also offers an emotional response that is impossible to achieve with other materials. Next only to the use of plants or the fish themselves, the use of wood in your design will illicit the most positive comments.

Beyond the esthetics, the biological advantages of wood are well documented. Many fish like or need to chew on woods. The tannic acid released by the wood can lower pH. The released tannin "stains" the water a brown/yellow color and lends a "blackwater" feel to the tank, subduing the light levels and perhaps comforting the fishes. Some fish like to breed in the crevices of wood.

Unfortunately, many many "old wives tales" exist regarding the use of wood. How to treat it, where to find it, is it safe and other questions tend to be answered in seemingly contradicting manners on the Internet. It is important to use your own good judgement when sourcing and then curing wood for use in you aquarium.

We have collected a number of common and reoccurring questions from the Internet. We have taken the questions and various responses and attached comments for your consideration.

When you consider adding wood to your tank, consider adding oak leaves at the same time. Not only will you get excellent pH lowering qualities, some fish go crazy in the leaves. Some Apistogrammas and Betta species respond very positively with the addition of leaf litter. The fish love the littered bottom and talk about a cool visual effect!

But what inspires you to use wood. For use, a walk along a beach can be a big help...wading in the shallows of a lake or in a stream also can help. Taking photographs helps to create an archive of "cool" things you have seen. Wood and the structure it can present in an aquarium can be though of as "Aquatic Bonzai"...small things made to look like big things.

We hope that this material will help you in finding and curing safe wood decorations for you aquarium. If you have any questions, feel free to email us.

Good luck,
jim

Stuff to think about…

I would like to use driftwood as decoration in my tank. How can I treat the wood (I have bleached, and boiled the wood) to make it safe. Can it pollute the tank? If so how?

Why did you bleach it? Getting the bleach out of the grain of the wood may prove to be as difficult as killing any parasites that may have invaded your tank.

Bleach is unnecessary…boiling will take care of just about anything except pollution.

If the wood comes from a polluted source you may have a problem in your future. You might want to think twice about the source of the wood. If the source of wood is polluted by chemicals, find another source. It’s a big country.

Another alternative to cleaning it is to soak it in a copper solution.

Why? If the wood is so problematic that you have to use a bunch of chemicals find another source.

How about baking the driftwood in an oven after washing off as much dirt before hand. A temperature around 200F shouldn't harm the wood and wood probably kill off any nasty organisms present. Does this sound feasible?

Sounds feasible to me. Just be careful of the 200F. The point of ignition for most woods may be higher than that but the little bits and pieces that hang off of the ends and edges may get a little singed.

In order to kill everything in the wood you will have to heat it long enough to make sure that the interior gets hot enough to do the job.

Can I pick up a really nice piece of driftwood from a landscape supply yard?

The wood may be "preserved"...it might be injected with insecticide...they do this with manzanita burls and roots mostly...ask them. In all likelihood it will be fine because the preservation process is expensive.

Another challenge you have to look for is buying the decorative wood in some craft places. That source is more that likely to be preserved (fumigated) so that the wood will not harbor bugs on a coffee table.

If I repeatedly boil it and drain the water until the water is clear will the wood will be properly conditioned and safe for use in my aquarium. Will that kill all of the parasites and bugs?

Yes...boiling drives the air out of the wood to help make it sink. Most woods don't sink like a rock during the best of situations, but they will sink and stay where you put them...ironwood will sink like a rock...oak sorta...manzanita better than some. Boiling will help to kill unwanted critters that may have resided on or in the wood.

The water is turning brown.

Well...I have had wood "bleeding" into the water for over a year...two

nice chunks are going strong after 18 months with 20% water changes each week...but it's a nice "blackwater" effect and I sorta like it. But don't expect the discoloration to go away.

Should I look for hardwood or softwood like pine. I heard that the pitch from softwood can harm the fish.

Hardwoods have pitch too, just a different composition and less likely to ooze from the wood over time. But then if you chose wood that has had the opportunity to weather and "drift" for several years, the pitch from hardwoods will be insignificant.

The pitch from softwood may ooze for years.

Safe wood is sold by many pet stores, why not stick with something that is safe?

I have yet to see the types of wood that I can find be available in my LFS. I have some pieces of wood that I purchased in the LFS, but for the most part I can create a unique and pleasant look in the tanks with found wood. Besides, when I do take time from the hatchery and travel, I like to pick up rocks and wood along the way. It’s my type of souvenir.

Someone mentioned that driftwood will lower the pH. I believe this is untrue.

The pH of my tap water comes out at just under 8, with the addition of a couple of pieces of wood in the tank and the pH goes down to around 7.5 after a couple of days. I believe that it is the tannic acid from the wood that is acting much like oak leaves or peat moss does in both softening the water and lowering the pH.

You might find that wood that is well weathered my have less effect on the pH as the tannic acid may have been leached form the specimen by nature.

Your pH drop will be affected by the buffering in your water.

The driftwood in my tank has continually stained the water progressively darker and darker brown, despite the water changes I implement (50%/week). Any short cuts to stop this besides time and patience?

Not really. The wood may continue to leach the tannic acid long after you tire of the aquascape and change it. Sometime you can add an extra cartridge of carbon to take some of the effect away. You will have to change the carbon more frequently with wood that is extremely active.

I soaked mine in extremely hot water for a few days. Doesn't color the water any more.

Sometime you can get lucky and pick up a piece of wood that does not leach too much. Soaking the wood over time (over the winter perhaps) may lessen the leaching or perhaps even eliminating it. Soaking does not always take away the challenge.

How long do you have to boil wood before sticking it in your tank?

We generally boil the wood for a day. That’s about 8 hours worth of boiling (simmering actually). The aroma (stink to some) is a little bothersome. We then let the wood sit in the water overnight in the hot water. The wood nearly always is sinking in the morning. We then wash the wood with clean water.

How long you think the wood was under or was it found out of the water?

I’m not sure what bearing this question would have on the quality of the wood or it’s safety in the aquarium. We often collect wood that has obviously been out of the water for a couple of seasons and when it’s boiled it sinks like all the rest and it’s just as clean.

Where do you think half the pet shops get their driftwood from?

They generally don’t lop it off the trees. They go where you go and buy it from importers and collectors. There are folks who collect wood for the craft and hobby industry as well as for the pet industry.

I've read in this new groups that having some wood in the tank makes the Pl*co a happy camper; most people refer to driftwood.

Why can’t use plain old heat-treated (but not chemical-treated) pine 2x4, and boil it similarly,

You can almost guarantee yourself that the 2x4 (or most other softwood lumber) will leach resins into the water. You might be able to find a local supplier of exotic woods (American hardwoods) would be found in the same place) and pick up a piece of scrap to carve. But you will still have to boil it and so forth. It would be much easier to find a piece of wood by the lake or the river (or ocean in my case) rather than take the risk of the new wood.

The driftwood pieces were pretty light weight, so I would suspect that they have been out of the water for quite some time. Is this bad?

You might want to give the wood a quick look over looking for soft (rotten) spots. Those will decay in the tank more rapidly. The decay is not a horrible thing but if you don’t have to keep an eye on a rotting piece of wood you will be happier.

I assume that not all trees are suitable for providing driftwood, since the wood from many North American trees don't look the same as driftwood found in LFS, and no one has recommend taking a branch from a backyard tree to use in an aquarium. Must the tree be of Amazonian or tropical origin? If so, why? Why can't the wood from any tree be use as driftwood?

The term 'driftwood' refers to dead wood which has been tossed and tumbled in water for some time. It is generally waterlogged and therefore relatively easy to sink and will leach a minimum of tannins into the tank water.

It’s more exotic sounding for the wood to be imported. I don’t know if the fish really know the difference. No the wood does not have to be of Amazonian or tropic in origin.

Just imagine getting wood from a tree containing analgesics and finding all your fish in a demented stupor the day after putting it in !

This is a good point. Eucalyptus would be a tree I might not want to use. I may be wrong on this point, but I won’t take the chance.

Can I pick a branch from the tree in the backyard?

Maybe but probably not a good idea. You might be using a dead looking branch that is still getting sap from the trunk. You can pull completely dry pieces from the tree and treat them as a piece of driftwood, but be sure you are using hardwood and not wood from a conifer.

Any driftwood or any other object brought in from outside with intention to put in your aquarium, should be completely sterilized. The best way is to boil the object. If it is too large, soak it in very, very, very hot water…You could put it in the bathtub and pour boiling water over it.

Maybe pouring hot water could work, but probably not. It is necessary to use heat over time…and a long time generally…to be effective as a disinfectant. Soaking in a tub outdoors for a season while providing frequent and complete water changes may be just as effective.

You might look into getting a kiddy wading pool. You'll probably have to weight the wood down, but a brink or two should be able to handle that.

I put a new boiled piece of driftwood in the tank. Now the tank is showing a kind of a yellow cloudiness. I have another driftwood that didn't cause this problem, but that one had been outdoors and been rained on and snowed on for 3 years.

Could the driftwood be the problem? I am going to remove it and sit it outdoors for a while. Maybe the tank will clear up.

Bingo. It’s back to that tannic acid thing again. You might not want to use the term cloudiness because that would normally be associated with a bacterial bloom. While the water is turning dark, it’s not because of bacterial infestation…that is if you have boiled your wood.

Putting the wood back outside may or may not work in a single season. You might consider some of the solutions offered like more frequent water changes and carbon filtration.