Dec. 2002: The following article will appear in a forthcoming issue of Ryedale Reporter, the monthly magazine of Ryedale Aquarist Society, North Yorkshire, England. Mr. Ali is a well-known figure in his local community who advises on the keeping of fish, amphibians and reptiles.
Bogwood is something I would recommend to all fish keepers as it has many benefits if added into a coldwater or tropical set-up. It's fine in the aquarium, providing it is thoroughly washed and prepared before putting it into the tank - there should be no toxins. Bogwood lasts a long time and makes an ideal shelter for many aquatic creatures including freshwater shrimps, coolie loaches and coldwater plecs.
To prepare bogwood for use you follow either a natural or poly-varnish process.
The natural process is as follows: -
1. Prior to adding bogwood into a tank it should be soaked in a separate bucket. This has the advantage of making the wood become waterlogged, at which time it should naturally weigh itself down when added to your tank. Also large amounts of tannin are released during this period and thus it is advisable to make plenty of regular water changes to the bucket. Be patient because although it can take as little as fourteen days for the wood to become waterlogged it can also be a two-month process.
2. Once in your tank there is no cast iron guarantee that waterlogged bogwood will not float. If you have problems keeping waterlogged bogwood in place then nylon cord can be used to tie the bogwood to a stone or slate (inert) in order to make the wood stay down.
3. Despite the steps taken at 1, tannin acid, brown-yellow in colour, will continue to be released by the bogwood, which gives the aquarium an Amazonian effect (good if you have any particular fish species requiring this, e.g. Cardinal Tetra). Activated carbon will remove the colour produced by the wood, and regular water changes also help.
4. Don't worry about the natural acidic tannin, as it does no harm to the fish.
When using the natural method three long term effects may be seen:
a. Bogwood can alter pH levels by lowering them, thus making the water acidic. Usually this is a long-term effect counteracted by making plenty of regular water changes.
b. If the bogwood is not petrified the living wood will rot underwater and grow a white fungus. This does not harm the fish and can usually be brushed off.
c. Parasites. I have not witnessed any such problems and always sterilise bogwood prior to use, by pouring boiling water over it.
The poly-varnish method is as follows: -
1. Thoroughly wash the bogwood under a tap, sterilise if necessary, and then leave to dry for a day or two.
2. Visit your local D.I.Y. store and acquire a product called 'Polyurethane varnish paint.' This pure clear varnish will lock in the bogwood tannin. Please note yacht varnish is also sold for this process but this should be avoided as it will harm all types of aquatic livestock. (It is actually manufactured to prevent mussels attaching themselves to boat hulls).
3. Use the poly-varnish once then leave to dry for a day, and repeat this for another two days (three days altogether). This makes the bogwood airtight.
The effects are no fungus, no release of tannin and no worries about alteration of pH.
As with all things that are good at face value there is a setback with this process in that the bogwood can no longer produce microorganisms or 'lignin'. Lignin is particularly important to many species of Loricarins (catfishes, particularly Panaque species) as it aids their digestion and meets certain nutritional requirements science does still not fully understand. Microorganisms add beneficial bacteria to the gut processes of many Loricarins also.
What is the solution?
If you don't mind a little work, add to your aquarium both a large piece of bogwood which has gone through poly-varnish process, and a small piece of bogwood of the natural process.
For help in putting together this article I send my thanks to Dr. David Ford and Dr. Peter Burgess (both of Aquarian fame), and Tim Henshaw (Bolton Museum).
By Majid Ali, Ryedale Aquarist Society, England
Tags: Aquariums Animals Biology Science Education