Freshwater Aquarium Basics

Updated April 29, 2023.

Warning! This article includes personal opinions and speculations!

The first advice I want to give anybody, who is interested and thinking about getting an aquarium, is to get plenty of knowledge first! In the aquarium hobby, there are some ways that often lead to failure, but there are also many different ways that can lead to success.

Usually, up to date aquaristic knowledge can be obtained directly in person from other aquarists, or indirectly from modern aquarium literature, social media, instruction videos, forums, Internet pages etc.

One of the best ways, to easily acquire aquaristic knowledge, is to join a local aquarium society and go to their meetings. (Do you have any active aquarium societies close to where you live?) Usually, you can get both practical help and locally specific advice from some of the members, to get a good start with your aquarium hobby. If you are lucky, you may also become friends with some of the members. You will probably choose to visit each other, or have fun together, at other times, besides the aquarium society meetings.

There are several different freshwater styles of aquarium keeping.

Before deciding on a style, ask yourself a few basic questions:

  • What purpose and intentions do you have with the aquarium?

  • What do you want the aquarium to look like in the future?

  • What appearance is acceptable right away?
    (Is gradual developent OK, or is instant excellence a priority?)

  • What kinds of fishes and/or various animals do you want to keep?
    (Diggers and others with special needs, may not suit all styles.)

  • Do you want to keep plants, if so, what kinds of plants?
    (Some plants with special needs may not suit all styles.)

  • What is your budget for the project?
    (Estimate your expenses for the first month, then also estimate them for the following twelve months.)

  • How much practical work are you prepared to do?
    (Do you want the aquarium to mostly take care of itself, or do you intend to often do regular hands on maintenance?)

  • Do you have a mentor, or any favorite aquarists, to guide you?

The quality, reliability, price and parameters of the water from your local water supply, is also important to consider, when choosing what general style of aquarium keeping you prefer to go with. For example, if the tap water is sometimes (or often) flushed with high leves of chloramine, or chlorine, you may choose to either go with a style of aquarium keeping that doesn't require much water changes, or you may want to invest in various testing products, water treatment products and set ups.

The reliability and price of the electricity from your local power company, is also important to consider, when choosing what general style of aquarium keeping you prefer to go with. If the electricity is sometimes (or often) spiking, and/or being cut off, you may choose to either go with a style of aquarium keeping that doesn't require much electricity, or you may want to invest in various spare products, in case they get damaged. Make a plan for backup power and/or emergency equipment, both for short and long power outages. If you want to cut down on the electricity bill, you may perhaps choose fishes that thrive in your normal room temperature, so you do not normally need to heat (or chill) the aquarium, during most months of the year.

The reason why knowledge is so important, is that too many beginners go and buy the wrong things, do things the wrong way, and because of that, unfortunately often fail completely. The fishes and plants do not make it, the glass walls get coated with ugly algae and/or cyano bacteria, while the aquarium stinks like a sewer. After that, the beginner often loses all interest and never wants to take care of an aquarium again.

Some simple advice, that could probably have made the beginner's catastrophy into a success, is, for example, to begin with an aquarium that is large enough, in comparison both to the individual size of fishes and number of fishes. It is more difficult to maintain a balanced ecosystem, with normal fishes, or larger sized fishes, in a small aquarium, than in a larger aquarium. Large aquariums are more forgiving and stable, in that they can better deal with various problems. Diluting can often delay the full effects of many problems, that in smaller aquariums would proportionally become much bigger problems, potentially catastrophic, if the situation develops beyond the limit of what small aquariums can handle.

In my opinion, a generally good size to begin with, if you intend to set up a normal community aquarium for the first time, is an aquarium of about 30 to 40 US gallons (110 to 150 liters). If you intend to keep fishes that eventually require an even larger aquarium, when they have grown up, then I strongly suggest that you either get a bigger aquarium from the beginning, or choose other fishes.

For a beginner, it is important to avoid overpopulating the aquarium with fishes. Otherwise, it will quickly become an unhealthy environment. If the microorganisms can't cope with breaking down waste matter from the fishes, the water quality can quickly deteriorate. You are not supposed to feed too much either, especially in a newly set up aquarium, but this can be very difficult to estimate for a beginner. Another common beginners' error, is to completely shut down the aquarium pumps and filtation during the night. Do NOT do that! If you choose to use airpumps and/or waterpumps, especially if they also run your biological filtation, then they should generally be running both day and night.

After buying an aquarium and all the equipment, I suggest to set up the aquarium and let the aquarium both "cycle" and get initially matured, with water and some hardy plants. Perhaps, some hardy algae eating fishes, shrimps and/or snails may also be added during the initial aquarium maturation process.

More fishes should, preferably, not be added until after a few weeks from the set up start date. After adding those fishes, I recommend to let the aquarium continue to develop a healthy environment, before evaluating if more fishes should be added after that. Although the initial maturation process helps, a newly set up aquarium with fishes added after a few weeks, will usually still not be as stable as a fully matured and seasoned aquarium, that has been maintained properly for years.

Unless you are prepared to frequently do regular water changes, it is safer to avoid fully stocking the aquarium in the beginning, during the first couple of months. If the fishes were young specimens, they may eventually grow and take up more space in the aquarium. If the fishes were already adults when they were added, they may perhaps reproduce and the offspring may take up even more space. This lets the aquarium ecosystem gradually adapt to dealing with an increasing bioload.

It is possible to speed up the maturation process significantly, by using a healthy mix of tiny living microorganisms, from all three domains of life (Archaea, Bacteria and Eukaryota). Many benificial microorganisms live on and in muck, gunk, sludge, mulm, filters, sand, gravel, leaves, wood, plants, or in the water column etc.

Benificial microorganisms can be sourced from already well established aquariums, or ponds, or outside in the wild nature, from where you can collect "seed cultures". There are also various products in the aquarium trade that claim to do similar things. Such products probably won't be as diverse as "seed cultures" from "real" sources, but may still be helpful. Using these tricks, you can add more fishes much sooner, maybe even right away, if nothing goes wrong. However, to be on the safe side, I still suggest to preferably wait a bit more before adding fishes, unless it is an emergency situation, or if you have plenty of experience and an excellent and abundant "seed culture" and suitable water available.

Be aware that the "seed cultures" should ideally originate from sources with similar water parameters, as the water parameters in the new aquarium. If not, the beneficial bacteria and other microorganisms may not properly survive and thrive right away. (It may still partially work, even if the water parameters are not so similar, but it may take more time and it is not as efficient.) A downside to "seeding" the aquarium using "seed cultures", is that you also risk getting unwanted types of algae, pests and diseases, especially if you choose a less than excellent origin source.

Depending on where you acquire your plants, they may potentially bring with them unwanted algae, pests, diseases and toxins. Many international exporters of aquarium plants are required to disinfect the plants before shipping, often leaving residue of the disinfectant on the plants. Some aquatic plants excrete irritants, when disturbed and being moved about, that in nature may help to protect them. When dealing with such plants, it may may not be good to handle them with bare hands, especially for people with sensitvity towards them. It may also be detrimental to some aquarium inhabitants, if the plants are put directly into their living environment, especially if you don't dip and rinse the plants (in a water barrel etc.), to get rid of most of the potentially harmful chemicals.

If you are rinsing large quantities of newly imported plants, I suggest to wear long sleeved protective gloves and discard the potentially contaminated rinsing/dipping water. The plants may also have gotten physical damage in transport, or from getting replanted etc. If you buy plants, choose the source carefully, and/or consider setting up a quarantine tank (or temporarily use a water barrel etc.), specifically for the plants. This is in case you need to treat and/or trim them somehow, to deal with any problems that may pop up, or simply wait until after the quarantine period is over and they have passed your inspection.

If you intend to use your local tap water for your aquarium, investigate if it always, or sometimes, has high levels of chlorine, and/or chloramine. If so, I suggest using any of the suitable products on the market that can neutralize chlorine and chloramine. However, if you intend to keep invertebrates as pets (such as shrimps, snails etc.), I suggest choosing a product, that clearly states on the label, that it is especially recommended for use in aquariums with invertebrates.

The time before buying more fishes can also be used to see if there are any problems. Such problems could be water leaks, or you may realize that perhaps the initial placement of the aquarium might not be optimal for some reason. There may also be something wrong, or inadequate, with the decorations, gravel, sand, or soil etc. Equipment failure is also possible, such as defective (or incorrectly used) lights, heaters, thermometers, pumps, filters, testkits, RO/DI system, CO2 etc.

You can take some time to check if you have forgotten something that you may want, such as maybe a timer for the lights, a new better light source, an automatic fish feeder, or a few buckets, hoses, nets, tweezers, scissors, towels, plant fertilizers, algae scraper and/or algae cleaning sponge/pad etc. (If you use sponges/pads, make sure they are without toxic substances and also without hard polishing materials. Don't poison your water with anti fungal chemicals etc. Also don't scratch your aquarium.) It is very common that something vital is missing, or may be broken, or inadequate/insufficient, if everything was bought second hand. New equipment may also sometimes fail and/or need some calibrating/adjustment, to work properly. Some filters may be difficult to disassemble and reassemble properly, or it may create noise, or excessive vibrations. It is generally easier (and safer) to fix (or exchange/upgrade) such things, before stocking the aquarium with fishes.

It can take some time to investigate exactly what type of fishes you truly want to keep, before buying them. Try to avoid buying random fishes on impulse, if you are a beginner in the aquarium hobby. I suggest to read up on all the different fishes you want and also choose from where to buy them, before you actually buy them. Besides reading texts and looking at pictures, I also suggest to look at various videos and at real living fishes, since their different behaviors can not be fully expressed through only a few still images and words. Your project will have a greater chance of success, if you educated yourself, about the species you want to keep, before stocking the aquarium with fishes.

As a final precaution, you may also ask advice from the aquarium shop attendant (and/or shop owner), from where you probably intend to buy the fishes. Make sure to mention how long your aquarium has been set up and any other essential information, such as the size of the aquarium, water parameters and equipment etc. If you want, you can also write all the most important information down and take a few pictures of your set up, then print it all out on paper (and/or save on your mobile phone etc.) and bring it with you to the aquarium shop.

I personally think it's beneficial to take the process, of becoming an aquarist, in a steady and calm manner. Build up a resonably solid foundation, of basic aquaristic knowledge, regarding the style of aquarium keeping you want to try, before setting up an aquarium, unless you also get practical hands on help, from an experienced aquarist you trust, to set it up. Try to avoid acting rashly, if you want the aquarium hobby to be enjoyable, both on a short term and a long term basis.

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E-mail Max Strandberg