If you’re new to fish, you may have wondered what kind of filter you should use in your aquarium care. Many brands of filter have a printed number on them that is supposed to indicate what size of aquarium it’s good for, but this number is only correct some of the time as each type of fish and various stocking levels have different filtration needs. The general rule of thumb is that the filtration should allow for the entire water volume of the aquarium to cycle through the filter four times every hour (the turnover rate); however, a number of factors can affect this number.
First, take into account the number of fish you have and the size of the aquarium. For fish under 6″ you will want approximately one gallon per inch of the adult size of the fish, over 6″ the fish need a tank that is at least four times as long and twice as wide as the fish. It is possible to keep more than the recommended stocking level in the aquarium, though it will require a lot more work to keep the water in excellent condition and to ensure that no issues arise due to the restricted space. If you have a higher-than-recommended stocking level, additional filtration will be needed to compensate, often upping it to a turnover rate of 6-8 times every hour. In some cases, water maintenance products such as EcoBio-Block can aid in keeping the water within acceptable parameters if the fish are overstocked, though this should be avoided as the fish also need individual swim space and sufficient oxygen for all inhabitants.
Special space and filtration requirements apply to goldfish, cichlids and many large carnivorous fish. These fish still need the same kind of space recommended for their size, but in general need a turnover rate of ten times every hour to provide sufficient oxygen exchange and mechanical removal of waste and uneaten food. These fish have larger stomachs than the average tropical community fish and so produce much more waste. Bear in mind that goldfish and fish such as oscars and piranhas reach an adult size of a foot or more so be sure to plan accordingly; it’s a particularly nasty myth that these fish grow to the size of their containment and no larger. While growth hormones will stop them from growing when there is no more room to do so, the fish will generally have shorter life spans and can have many other health issues; oscars and gouramis, amongst others, will only experience a cessation in the growth of their head while the body still grows — eventually, their mouths will morph too much for them to be able to eat.
In many cases, the type of filtration must also be considered. My favorite filters are HOB filters that hang on the back of the tank and remove waste while facilitating oxygen exchange by keeping the surface of the water moving; however, HOB filters do not work for all fish. Because of the current produced by the workings of the filter it is not the ideal choice for weak swimmers such as bettas and smaller angelfish, while its open intake makes it dangerous for tiny creatures such as fry and shrimp. For these fish, sponge filters or undergravel filters coupled with good aeration may be the best option.
There are some measures that can be taken to lighten the filtration burden in your aquarium. The best thing for any aquarium is to have healthy inhabitants and for that you need the best possible water quality, meaning timely partial water changes as well as a strong biological filter. Biological fitration is achieved by having healthy amounts of bacteria in the aquarium and can be helped along by commercial water maintenance products such as EcoBio-Block. EcoBio-Block not only helps by adding good bacteria to the water, it also provides the essential minerals that are used up by fish and would otherwise have to be replenished through partial water changes alone.
It seems that I begin many of these letters by quoting from some correspondence. After all, what better or more practical source of inspiration can there be? In this instance, the point is one that is brought up rather frequently by beginners in aquarium care, who have not been very successful after having seemingly followed the primary instructions gleaned from books or our dealer friends. They give recommended foods in conservative amounts, have good light and temperature control. But here is where trouble starts, through the acceptance of a fallacious signal as to what constitutes “overcrowding.” The signal watched for is when the fishes gasp at the surface of the water, “blowing bubbles.”
That is a carry-over from the days when goldfish was King. Goldfish and other cool-water fishes are very sensitive to any shortage of oxygen in the water, or the presence of too much carbon dioxide. They quickly express their distress by breathing at the surface. Incidentally, I have often wondered how fishes, never before in such a situation, know enough to get a fresh supply of oxygen at the surface of the water.
Warm-water fishes are better equipped to get along in oxygen-deficient conditions. In a tank containing both goldfish and exotics (a combination not recommended) the goldfish will invariably be the first to register discomfort from overcrowding. The point that I am stressing is that “Tropicals” are apt to “suffer in silence.” When they come to the surface and stay there, conditions are not merely bad, but very bad. Undetected crowding has been present for some time past, indicated by the poor condition of the fishes. Of course such symptoms can come from other causes, but crowding is one of the first to look for. That suspicion can be confirmed if frequent partial changes of water relieves the condition.
Water changes help keep the parameters within acceptable limits, help remove excess organic material such as waste and uneaten food, and also replenish required minerals in the water that the fish use up over time. If you prefer not to do as many water changes or are physically unable to, there are alternatives that can reduce your labor. My favorite is the EcoBio-Block, which is an aquarium care product that introduces beneficial bacteria into the aquarium (which keep the biological filter healthy) and slowly leach necessary minerals into the water to keep fish healthy and help beginners become successful aquarists.
Advising a new aquarist at the height of his frenzy to go slowly in building up his tank of fishes is like talking against the tempest. Recently I fitted out a grandson with an aquarium and a suitable collection of fishes. All was lovely for a few weeks until he was bitten with the desire for more and more.
The dealer could not be blamed for selling to him, but the result was not hard to foresee – a general attack of “Ich.” Overcrowding does not necessarily cause that disease, but reduces the vitality of the fishes so that they are more subject to it.
The elder Rothschild is credited with the wise crack “Nobody ever got poor taking a profit.” I would paraphrase that in reverse: “No aquarist ever got into trouble by having too few fishes:”
When you are ready to purchase your first aquarium, one of the first things you learn is how to properly cycle the aquarium and how to slowly introduce new fish to avoid ammonia spikes while the colonies of beneficial bacteria are developing. That’s easy enough to follow — but what about when you have to move an existing community of fish to a new home? Maybe you moved and have to re-establish the aquarium, maybe you’re moving to a larger or even a smaller tank; whatever the reason, there are ways to safely move the fish without as much risk of ammonia spikes.
A properly cycled tank contains a healthy colony of bacteria that breaks down ammonia from a fish’s waste and uneaten food into nitrites and then into nitrates. In a healthy tank, there should be 0 ammonia, 0 nitrites and less than 40ppm nitrates (20ppm if you have invertebrates such as snails or shrimp). Without sufficient amounts of beneficial bacteria, ammonia and nitrite in the water may be fatal to fish.
Beneficial bacteria live all through the water and on every underwater surface in the aquarium, but the water itself carries a very low concentration of bacteria so it’s not very effective to simply transfer water from the old aquarium to the new in order to maintain bacteria levels. Ideally, you will be able to transfer some old filter media to the new aquarium, or even a handful of gravel or fake plants that will all have beneficial bacteria on them. Make sure that the materials of your choice stay wet with tank water until they can be placed in the new aquarium.
Alternatively, if you have EcoBio-Block in your aquarium, that will be sufficient to switch over to the new one. EcoBio-Block has a lot of beneficial bacteria living in its volcanic rock and has quite a bit of surface area so a lot of additional bacteria get transferred over from the established tank. It is not necessary to keep EcoBio-Block wet, but it may help eliminate any minor ammonia spikes that may occur after the transfer as there will be more active bacteria immediately if kept wet. EcoBio-Block will also allow you to wait a little bit longer before doing the first water change as it provides essential minerals that would otherwise have to be replenished through water changes, giving the fish extra time to de-stress after a big move without being bothered.
Make sure not to put whatever bacteria-containing materials you’ve chosen into the new aquarium until a de-chlorinator has been used in the water as chlorine will kill the bacteria. Keep close tabs on the water parameters for the first week after the transfer, doing minor water changes as needed to compensate for any ammonia in the system that may not be compensated for by the bacteria yet. Watch the fish closely for any clamped fins or red, puffy gills as these may be signs that the water parameters are off. If these simple guidelines are followed your fish should have a relatively effortless and healthy move.
