There have been many common and potentially dangerous myths about fish keeping handed down from LFS to hobbyist for generations. In this article we are going to try to dispel some of the more common ones. This guide is aimed at beginners so that they do not fall foul of these myths. If anybody wants further information or discussion about these topics please feel free to search the board, or ask your own questions.
There is no need to run carbon filter pads in your filter all of the time despite what the instructions in your new filter manual will tell you. Carbon is used to remove unwanted external chemicals from your tank and therefore the most common use of carbon is to remove medication from a tank after a course of treatment.
There is also the fact that carbon absorbs chemicals, but these absorbed chemicals can be replaced by other chemicals that are more readily absorbed by the carbon at a molecular level. Therefore there is a risk that old carbon in your filter can actually start leaching unwanted chemicals back into your tank. It is worth keeping a sealed carbon filter sponge in your fish cupboard for emergency use.
Changing Filter Media every month
Again many instruction manuals for new filters suggest you replace filter sponge media every month / 2 months / etc. If you consider that the beneficial cycle bacteria live within these filters, carrying out this suggestion will result in your filter cycling every month and therefore exposing your fish to toxic chemicals regularly.
There is no need to replace your filter sponge media until it is literally falling apart in your hands (this will usually be at least 10 years and is generally longer than the life span of your filter pump). To maintain your filter sponge media simply rinse half of the media in used tank water every month or so or whenever the flow through the filter is reduced.
Changing filter wool (filter floss)
As with filter sponge media, filter floss does not need to be replaced until it is physically falling apart when it is handled. The primary purpose of filter floss is to filter solid waste from the water. Therefore this media is what will contain most of the gunk that we get on our tanks and will therefore require rinsing more often than the sponge media.
There is very little friendly bacteria resident within this media, so there is little harm in replacing it periodically, however it can be regarded as an un-necessary expense rather than the necessity that your filters manufacturer will often state in the manual. If you do choose to replace this media, then it is possible to buy sheets of filter floss and cutting / folding it to size in order to fit inside your filter housing rather than paying for expensive branded media.
Nitrate removal sponges
The cheapest most effective way to remove nitrates from your tank is to change water. The effectiveness of these sponges is open to debate, however they should not be considered as a suitable substitute for regular water changes, as nitrate is not the only unwanted chemical that is removed from a tank during a water change.
There are many other chemicals and hormones that your fish excrete that we do not test for, but are best removed from the tank via water change (Waalsted theory excepted, but this is not for beginners). If you do have these sponges in your filter, then there is no problem with just leaving them in there as if they were additional bacteria housing sponges, they therefore do not need to be replaced until they are physically falling apart in your hands as detailed above.
Water Changes and Tank maintenance
As discussed above, maintenance of your filter simply requires that you rinse out the filter media in used tank water to remove the gunk. You do not want to be too vigorous with the cleaning as this may result in the loss of beneficial bacteria.
One significant myth is that large water changes are bad. This is only true if there is a large difference between your tap water statistics and your tank water, however if you keep your tank water close to the status of your tap water then there is no harm in carrying out very large water changes even above 80%. You should note that for many species the river that they originally come from have water changes of well over 100% every second even in relatively slow moving rivers.
If there is a difference between your tank water parameters and your tap water, then it may be worth starting a new thread to get advise on how to proceed, however if there is no ammonia present, then 20 - 30% water changes on a daily basis shouldn't be a problem.
Leaving a new tank to Stand for a week / 2 weeks / 3 days, etc....
It is a common myth perpetuated by many fish shops that has no basis in fact at all. Many LFS call it a settling period, a cycle, or even a fishless cycle. Unless there is a source of ammonia in the tank, then there will be no growth of a beneficial bacteria colony and therefore there is no benefit to leaving a tank to stand in this way.
Also note that a pinch of flake fish food or adding a frozen prawn is not sufficient to provide the quantity of ammonia required to establish a bacteria colony large enough to support a full tank stock and can be ignored as far as this myth is concerned.
Bottled Bacteria Supplements
There are many products on the shelf that claim to aid or establish the development of the beneficial bacteria colony. These products often claim to contain the beneficial bacteria, however they are usually stored at room temperature on a shelf in the fish store for months at a time and have use by dates in excess of a year. This begs the question, how is a living bacteria going to survive in a closed bottle with no food or oxygen source for such a long time period? The simple answer is that it can't and in the main the products are worthless.
There is currently only one product reported by reliable users of this web forum that has any worthwhile effect, it has a very short shelf life and must be stored and transported in a refrigerated environment and is only available in North America, its shelf life and transport requirements are such that it cannot be exported to Europe or other parts of the world.
First off I strongly suggest that you read the Nitrogen Cycle article to get a good basic understanding of the process to help you understand what it going on in your tank.
Whilst most people refer to it as cycling a tank, you are actually cycling a filter. It is not possible to cycle a filter without a source of ammonia, therefore when the LFS suggest that you fill a new tank with water and leave it for a week to "cycle" they are wrong and it will not cycle as there is no ammonia in the tank.
There is virtually no beneficial bacteria in the water column, therefore getting tank water from somewhere else does nothing to help.
Many LFS will suggest that you should not carry out a water change during a "fishy" cycle. If you can measure ammonia on nitrite using your test kit, then there is more of these chemicals in the water than the current bacteria colony can consume and therefore the bacteria colony will reproduce until it no longer has an excess of it's food supply. Carrying out even a very large water change will not completely eradicate the excess bacteria food from the water and therefore the bacteria colony will grow whether a water change has been carried out or not. Obviously diluting the concentration of toxic chemicals will have a significant benefit to your fish and as I have explained, will not slow the growth of the bacteria colony by any significant margin.
Fish only grow to the Size of the tank
In one way of thinking this is true, but in a very bad way. A fish kept in a tank that is too small for it may become stunted and this may end up with serious internal problems with its skeleton and internal organs. The end result for many stunted fish is early death, but prior to that they are stressed and more prone to disease.
You need an air pump
Oxygen is transferred to the water at the surface. Therefore anything that breaks up the surface of the water gives extra oxygen transfer and will increase the oxygenation of the water. An air pump does this, but is unnecessary as simply pointing your filter outlet towards the surface of the water increases surface agitation and therefore oxygen transfer. If you want an air pump for aesthetic reasons then go ahead, but don't assume that it is required.
You have to have a certain PH value
Fish are entirely unaffected by Ph within the range 5.5 to 9.0. In fact the range could well be wider than that, but filter bacteria efficiency reduces as the PH drops and the filter bacteria go dormant and start to die off before the fish start having any problems due to PH.
Fishkeepers who have considerable planting and CO2 injections systems often report changes in PH by over 1.0 within a few seconds of the CO injection system operating with no ill effects to the fish, thus proving that fish are able to cope with very large changes to PH several times every day.
Of considerably more importance to the fish is the Total Dissolved Solids (TDS) in your water. TDS is usually related to hardness and hardness is often indicated by PH, but they do not always have to correlate. Fish that are traditionally known as soft water low PH fish are in fact intolerant of high TDS, and conversely fish that are known as hard water high PH fish are actually intolerant of low TDS. Whilst it is possible to purchase a TDS meter, this is generally considered unnecessary as the PH and water hardness relationships are usually true, and therefore a safe estimation of TDS can be made from measuring PH, GH and KH.
The use of the PH up / down / all around type products is not recommended and can cause more problems that they attempt to solve. Whilst the Ph is unimportant, adding unnecessary chemicals to your tank is never a good idea.
You need to add Aquarium Salt
2 points here:
1) Aquarium salt is just an expensive version of ordinary table salt and there is nothing wrong with buying the significantly cheaper version from your local supermarket
2) Many LFS advocate adding salt as a general tonic to prevent disease. However salt dipping should only be carried out for very specific purposes and at a much higher concentration than you would add to a community tank anyway. Adding salt to a community tank will have a significant detrimental impact to many intolerant species which are very common within our hobby and disease / parasites can become resistant to it.
If have a sick fish that you think will benefit from a salt bath or other salt treatment, then start a thread on the subject and get advise from the experienced fishkeepers on the board before you try treatment. One of the main beneficial uses of salt is to counter nitrite poisoning, where salt ions will out compete the nitrite ions for absorption into the fishes bloodstream. Whilst this is not a substitute for water changes to reduce the concentration of nitrite until the cycle bacteria catches up with the excess nitrite food supply, it is worth considering as a temporary measure whist there is excess nitrite present. The dosage for this is half a teaspoonful per 10 US gallons of water.
Snails are bad
Snails usually come into your aquarium as eggs on plants and it is almost impossible to stop them. Whilst they can look unsightly, they contribute very little to the biomass of the aquarium and can be virtually ignored from any estimation of stocking capacity. It is possible to argue that the snails offer a positive additional to the aquarium as they consume any uneaten food and also consume other waste within the tank.
There is a suggestion that soaking any new plants in a copper container for a few days will eliminate snails, as they are not tolerant of copper. In theory this will be true, but at the moment we have no guidance on how long is required to kill off all snail eggs on any new plants.
Getting a fish such as a loach to eradicate snails is not an good idea, as without proper research and planning you may end up with a fish that is not appropriate for your aquarium and as the snails often live inside the substrate and the filter housing the fish will not be able to complete the job that the LFS suggested it would anyway.
You should get an Algae Eating Fish (clean up crew?) to keep your tank clean
Many LFS will suggest that an algae eating fish is required, will keep your tank clean, are scavengers that do not contribute to tank population and should be ignored from capacity calculations. This is untrue as no fish will completely eradicate your aquarium of algae, therefore they will never represent a substitute for elbow grease and a regular maintenance regime, you also have to add supplementary food for these fish, they still produce fish waste (poo etc) and they also need oxygen to survive and therefore cannot be ignored from any stocking capacity.
Again it is not good practice to buy a fish for a specific job within your aquarium, as you may end up with an inappropriate fish that will cause you more problems and will not solve the one that the LFS suggested it would anyway.
Whitespot is caused by stress or Whitespot is present in every tank
Whitespot or Ich is a parasite that has a lifecycle. It is not present in every tank and whilst stressed fish are less able to fight off a parasite attack as well as healthy fish, they cannot get whitespot unless the parasite is present in your tank.
The whitespot parasite usually enters your tank when an infected new fish is added to your aquarium, which is why most LFS like to perpetuate the myth that it is present in all tanks, as it deflects the blame away from the fact that they sold you a fish that was infected. This is one of the many reasons why quarantine tanks for new arrivals is so important.
The parasite cannot survive for long in your aquarium without a host fish to feed on. This is why it is not present in all aquariums, as newly setup aquariums without fish are certainly clear of the parasite and even a used aquarium that has been empty for a relatively short amount of time will be clear.
Beneficial bacteria are found in the water column
As detailed above, the beneficial bacteria that is part of the nitrogen cycle lives on surfaces.
Therefore as the media within your filter is designed to have a very large surface area, most of your bacteria lives within the filter media. As the water in your tank does not actually have any hard surface for the bacteria to grip onto it has no bacteria present and is therefore worthless when it comes to cycling a new tank.
Guppies / Platys / Neons are good first fish to cycle a tank
Firstly I would strongly suggest that you carry out a fishless cycle rather than cycle a tank with fish. However many LFS will suggest that you add "hardy" fish to cycle your tank and then many of them point you towards Guppies and Platys.
Due to line breading for specific colour strains these fish can certainly not be described as hardy anymore, with fancy guppies particularly fragile nowadays. Indeed Neons and a few other common species do better in a more established tank, therefore you should do your research before you buy your fish to ensure full compatibility within your tank.