Starting a new aquarium is the first step toward an educational and relaxing hobby. There is much to learn about animal behavior, water quality, and the rich and beautiful life below the surface of the water. Traditionally, hobbyists gained this knowledge by speaking with an involved aquarist; however, in recent years people have taken to believing that they know best because they read something on the Internet.

The Internet provides a wealth of information – some of it quite useful, but what do you actually know about your source? Are they selling something? Are they fishing for hits on their page? I encourage everyone to gain as much information as possible, but there’s still nothing better than talking to someone experienced in the art of aquarium care and maintenance.

We first covered this essential topic in one of our first stories for our old print publication of Total Pet Magazine. We’d like to update and provide a refresher for new hobbyists.

Starting a New Aquarium

Real Fish Talk

I must be blunt here. If you don’t want to learn how to care for fish then you should not embark on this hobby. It does not take long to learn how to properly care for a starter aquarium. Many young children have had to suffer untimely toilet-bowl funeral services because of ill-prepared aquarium owners, and the experience turns them off the hobby forever. The parent needs to be involved to make sure that doesn’t happen.

Starting a new aquarium teaches us about animal behavior, the significance of water quality, and the physiology of animals living in the water. The adaptations required to live in beneath the surface of the water in 6-ppm (parts per million) oxygen is an area few think about. They’re just fish. There have always been fish. Fish are fish and not like other land animals — which is obvious, but sometimes needs reminding. Consider this: atmospheric air is 20,000 ppm. The physiological adaptations required to pull trace amounts of oxygen through the body of marine life is astounding.

Starting a New Aquarium

Consider the above image that we pulled from a website selling “Starter” Aquarium kits. The fish inside the tank aren’t even to scale — they were Photoshopped into the image. It’s making you believe that the number and type of fish contained within would be perfectly reasonable for a 5-gallon tank.

This is a first lesson in becoming a good aquarist. As I mentioned, beginning is easy, but don’t think for a minute that buying a kit and putting water in the aquarium is a good beginning. A box with a photo featuring a bunch of fish in a tank already has you headed in the wrong direction. Manufacturers want you to see a perfect tank with perfect fish – but I guarantee you that those fish were removed from that “perfect tank” the minute the photographer finished taking that product photo — if they were even there at all.

Fish and Retail “Service”

Once upon a time pet shops used to help customers – especially when it came to home aquatics. Even simple endeavors in the home aquarium hobby require a semblance of pre-existing knowledge. This is not a “see what happens” kind of hobby. Today, pet stores place a box on the shelf that includes “everything you need” to start an aquarium at home. The teaching element of the pet store/customer relationship has been transferred to a one-sheet instruction manual or redirected to the Internet. All you could ever need to know in under 500 words. Does that sound reasonable to you?

Today big box stores have virtually zero training for selling fish to customers. They sure can sell a fish (and most importantly all the “stuff” that goes along with it), but they don’t know the first thing about caring for it once you take it home. It’s not right. All animals in our possession deserve proper care. When these stores do manage to give information, how much can you trust the source knowing they’ve had no formal training or education on the topic? The hobby has deteriorated due to the dispensation of poor information. Why? It’s marketing to sell stuff without a conscience. They put aquarium kits on the shelf and believe that whatever you buy is your problem after it walks out the door. It feels criminal to me – though none of these criminals will ever be brought to justice for their crimes against Corydoras and Neon tetras.

Starting a New Aquarium

Step 1: Patience and Biological Filtration

The most important aspect of starting a new aquarium is establishing a viable biological filter. The biological filter is not a benefit you actively witness – except as it manifests in healthy, happy fish. The unseen “good” bacteria (the biological filter) degrade ammonia by growing colonies in the aquarium.

How does this happen? Bacteria convert ammonia to nitrite. If you remember high school chemistry this is called oxidation caused by the ammonia-oxidizing bacteria. This process only happens in the presence of oxygen. These bacteria are therefore essential to the nitrogen cycle.

Two major chemical steps establish the biological filter. The bacteria grow on the surface of aquarium gravel, the sides of the aquarium, plants (plastic, silk, and real plants), and the ornaments put into the aquarium. This takes about 45 days. I hear some misinformed pet store employees tell people that the biological filtration can be started with aged water. That is really not true. Aged water transfers some biologicals, but the best inoculants are substrates with the bacterial colonies attached. Old water, by itself, is just old. Using the bacteria from aged aquarium water has a very long lag phase to begin the process. In reality, it’s like starting from scratch anyway.

Ammonia and the Nitrogen Cycle

Let’s back up for a moment to discuss why this ammonia oxidation process is important to a home aquarium. Animal respiration results in ammonia. The degradation of uneaten fish food also causes ammonia. Ammonia is very toxic to fish. It burns their gills, affecting the protective coverings on their surface, and can affect their eyes.

The first step in the nitrogen cycle is to oxygenate the ammonia to make nitrite. The second step is to oxygenate the nitrite (toxic but not as toxic as ammonia) – again with the help of our friendly bacteria. This results in nitrates, which are stable in our aquariums, but need to be limited through regular water changes. This whole process, without help, takes about 45 days.

Booster cultures might build the bacteria faster but they are expensive. The best and most economical way is to start a tank on your own with some old aquarium gravel. Old gravel doesn’t mean the process happens overnight, just that it dramatically cuts the biological release time.

Ideally your biological filter negates the ammonia as soon as it’s produced. That specific point of stasis can be found with test kits. The first change will show nitrite. The second and final phase turns nitrite into nitrate. From that point nitrate will increase until water changes are made, which I recommend at least once a month.

Populating the Aquarium

When buying your first fish colony, make sure you only buy small fish – one or two for a 10-gallon tank. I like a Corydora catfish and a tetra combination. Feed sparingly every other day and watch closely to make sure they are eating everything you introduce to the tank.

Starting a New Aquarium

You can also bring in a Betta. The Betta is one of nature’s most beautiful fish and very impressive in a small starter tank. Due to their alternate name, Siamese Fighting fish, most people think that Bettas attack everything in sight. That is not true. For the most part, they only fight amongst themselves. One Betta per tank is plenty because it’s important to keep the peace.

…but not Overpopulating the Aquarium

During the introduction period, check your ammonia levels regularly, perhaps every other day, to be sure you are not feeding too much nor have you put too many fish in the aquarium. If you notice your ammonia levels rising that’s an indication you’ve overpopulated your tank or you’re feeding too much. First, ask yourself honestly if there are too many fish. Many times, the answer is too much food and too many fish. The next consideration should be a 50% water change. Respond with products like SeaChem’s Prime, NovAqua+ or Tetra Safe. Follow directions carefully. Use the above chemicals after the water change.

Starting a New Aquarium - too many fish

Our people are trained to ensure that customers do not start an aquarium with too many fish. Sometimes customers get upset with us because we believe that animal welfare always comes first. We’re in a customer service business, but we’re also in the business of pet care. If we believe there’s a potential risk to the animal we will refuse a sale. Inevitably, this angers people who then take to the Internet to leave us scathing reviews painting us as a condescending business that’s just trying to sell more stuff, e.g. larger aquariums, larger pet enclosures, etc. Or worse — these vociferous Internet executioners will claim we just don’t know what we’re talking about. It’s the nature of the pet business in 2018 – and really any service-focused establishment – but we will always risk a negative blurb on the Internet before the health of our animals. No one likes to be told that they’re wrong — especially when they mean well, and we understand that — but our job is to preserve the health of the animals. Trust us when we say it would be far easier to just give you what you think you want.

ipse se nihil scire id unum sciat — This, the Socratic Paradox, is perhaps the wisest piece of philosophy ever recorded. (Plato attributes it to Socrates, hence the name, but there’s no real evidence to suggest that Socrates ever made such a claim, but we digress.) The Socratic Paradox states that the only true knowledge is that knowledge that we know nothing. It suggests that there’s so much to learn and discover in this world that, relatively speaking, we know so little that it amounts to nothing. We would all be better served to remember these words whenever we undertake a new endeavor. Let’s get back to the fish.

After 30 days you can add a couple more fish. If the initial addition of inoculated gravel worked, the aquarist should see no ammonia spikes for roughly 20 days. In the past I have found that the ammonia disappearance is faster than the nitrite disappearance. Patience is required to set yourself for long-term success.

The number of fish an aquarium can hold is based on biomass. The widely held one-inch-per-gallon suggestion is absolutely wrong. For example, a 3-inch goldfish could weigh as much as hundreds of neon tetras. A three-inch goldfish should have 30-gallons of aquarium space and good filtration for the next 2 or 3 years before a bigger tank might be needed. Goldfish do not just grow to the size of their aquarium — unless toxins stunt their growth, which would be an indication of too much biomass per gallon of water. On top of that the toxins can affect the immune system. The fish dies much sooner than their natural life span. Do not believe that fish in general live no more than a year. Some fish — but not many.

Starting a New Aquarium - goldfish

To grow and prosper, the goldfish needs excellent filtration, ample water volume, and good circulation. I personally love quality-bred goldfish like the American Fans, Sarasas, and Calico – but no fish should be thrown in a tank and left on its own.

Early Aquarium Success

The key is behavior of a particular species and general hardiness of the species selected. I do not like tiger barbs for beginners. They display aggressive behavior toward all small, quiet fish. Purchase docile fish that stay small for a starter aquarium. A big mistake is purchasing common plecos for small tanks. They get large – for sure larger than a ten-gallon aquarium can safely contain. People buy them to keep the aquarium “clean.” This is perfectly logical, but ultimately wrong. Plecos do eat some things that help keep the tank appearing clean, but unfortunately the actual tank cleaning is human work. As a rule of thumb, if the fish is too large for a tank give it to someone that can properly care for a bigger fish or trade it to a receptive aquarium owner that has the ability to sell the fish a proper home.

Some of the smaller tetras like Neon, Cardinal, and Von Rio serve as great beginner aquarium fish. Once the keeper gets their feet wet, so to speak, Otocinclus and Farlowella catfish could be considered Level 2 species. These fish can be added without concern about territorial disputes.

Back to Aquarium Water Chemistry and pH

Now let’s return to our discussion of water chemistry. It doesn’t matter what you think about aquarium keeping, understanding basic chemistry remains an integral part of the experience. So, let’s go over another important concept in starting a new aquarium.

Try to keep your pH (level of acidity) around 7, which is neutral. All fish and freshwater invertebrates and decaying food and plants produce carbon dioxide (CO2). CO2 dissolved in water produces a Carbonic acid, which reduces pH. Therefore, maintaining pH requires constant vigilance.

How do we regulate pH? Use a buffer. For beginners I like Seachem’s Neutral Regulator. Do not use pH Up or Down. These two chemicals are not buffers and have limited use in aquariums with ground water from limestone aquifers. pH Up can be used in bog-sourced water, which is acidic in nature, but the buffer is still needed to help stabilize the pH. Limestone, meanwhile, raises pH and hardness (Calcium and Magnesium).

A more advanced aquarist will use reverse osmosis water to replace aquarium evaporate. This will keep the hardness from continuously rising. I love RO water, but most people don’t want to use it because of the perceived hassle involved. The hassle to set up an RO system is, however, rather minimal, and it will save you money in short order.

High hardness is easy to control, however. Most fish will accommodate to rising hardness as long as the level isn’t too much for them to handle osmotically – but we’ll discuss hardness control in a more advanced course on water chemistry. For now, let’s just get that pH under control.

Types of Filtration for Beginners

Do not let anyone talk you into buying a canister filter. The sales pitch suggests it is an all-inclusive filter creating biological, chemical, and particle filtration. The sales people tell you it is convenient and convenient is better. Hogwash. Two words: particle filtration. Canisters are serviceable biological and chemical filters, but they do not benefit overall, long-term aquarium maintenance. If not maintained, they can become detrimental. When the hobbyist tires of maintaining the canister, they skip cleanings. When they skip cleanings the decomposable organics disintegrate and add dissolved proteins to the water which increases phosphates and nitrates. More pre-filter maintenance results in aquariums with greater pollution resistance. Canisters, for all their bells and whistles, are also relatively expensive. (Have you figured out why stores would try to sell you a canister system yet?) While they’ll lure you in with the promise of convenience, they will eventually increase your work.

Let’s think about this canister filter problem logically.

Aquarium water shoots up through the filter from the bottom. The prefilter rapidly accumulates dirt and detritus, thereby slowing water flow. To remedy this, you must tear down the filter for regular cleanings. This is not something people will want to do. It is messy and takes a fair amount of time. Did I mention that this system of filtration also costs more? You pay for the fun of extra maintenance.

Sometimes old school is the best school when it comes to aquarium filtration. The oldest and most reliable filter systems are sponge, under-gravel, and hang-on filters. Let’s talk about each of these and weigh their benefits.

Starting a New Aquarium - sponge filter


The sponge filter comes in many shapes and sizes. They are simple but effective. Aquatop produces some nice sponge filters. One can also just buy the sponge and make your own filters, but that’s probably not beginner-friendly. Just know that the potential’s there when you get further into this new hobby.

For more biological filtration just increase airflow through the filter sponge to promote that good bacteria growth or add another sponge filter. When cleaning, use water from the aquarium to preserve biological charge rather than new water from the tap. New water will also wash away your established biologicals!

Even though sponge filters are not particularly “sexy” they are great biological filters, especially if you don’t have gravel. They come in various sizes to fit your tank size, but they do need to be biologically charged before use to be effective. If you take one out of a box, expect a 30- to 45-day wait in a cycled tank to be fully charged. They are great when raising fry and shrimp. Hang-on filters and canisters will suck those poor shrimples up inside the filter. Plus, growth on the surface of the sponges will help feed shrimp and early fry.

Starting a New Aquarium - under gravel filter

This illustration shows the air bubbles rising in the tubes bringing water to the surface. This is good for raising babies like guppies, mollies, platys, etc.


Another serviceable filter for the beginning aquarist. A plastic perforated plate is placed on the bottom of the aquarium beneath the gravel. There are two ways to set them up. The first is to use a powerhead on the standpipe and push the water from the aquarium through the bottom gravel. The downflow forces the water up and through the surface of the gravel. The second way is to use an air stone in the tube to pull water through the gravel and up through the tube. This is safer for small fish, but less effective for a community tank.

The downside to this method is that the mulm (black particular matter) must be periodically cleaned from the gravel and underneath the filter. The only sure way to do this involves pulling up all of the gravel and filter to clean the sediment from underneath the plate.

Starting a New Aquarium - biowheel


The water flows under the wheel and turns the cylinder. The wheel then rotates the water down through the filter. This is a solid filter, but the wheels will eventually need to be replaced. When that time comes, buy a new set of wheels and place them inside the aquarium to biologically charge before replacement.

Starting a New Aquarium - hang on filter

This is a typical hang-on filter. Notice the pump (powerhead) under the filter body. One primes the filter and the pump starts a siphon. The configuration of an external powerhead creates a bit more noise. The Aqueon filter immerses the powerhead in the tube reading up from the aquarium.


These have been around for a long time. A tube is placed in the tank that goes to the filter. The filter hangs on the back of the aquarium. The filter box is primed via the hang-on tube and the powerhead pulls water through the filter. These filters require cartridges (sponges for biological filtration, charcoal, and special things like ChemiPure) and other inserts as needed. As an alternative, a hang-on could feature an external powerhead pushing water through the filter. No siphon required and therefore less chance for that siphon to break. I recommend the Aqueon filter for this type of setup. The other benefit is that they are very quiet.

The Marineland bio-filter offers yet another variation. They developed a system called the bio-wheel. In reality, it is a type of wet-dry filter. The wheel turns because the water is pumped through it like a mill wheel. The water comes in contact with the wheel (and thereby the bacteria growing on the wheel). The bacteria purify the water by eliminating the ammonia. It is a bit more effective than the other hang-on filters because air contains more oxygen (obviously) to help neutralize the ammonia. In more simple terms, oxygen helps the bacteria work harder and smarter.

And speaking of the wet-dry filter…


The true wet-dry filter provides the most effective type of filtration, but beginning aquarists need to understand the mechanics before committing to the greater expense. They’re not difficult to implement, but as I suggested a moment ago, the initial set-up cost proves higher than the alternatives — largely due to the necessity of an overflow. As a result, the wet-dry filter generally remains a more popular choice among more seasoned hobbyists. I would not discourage a beginner to take the leap so long as they understand a few simple concepts.

  1. The sump beneath the aquarium increases the biological capacity of the aquarium.
  2. The aquarium will never show white lines from carbonate desposits.
  3. To replace water evaporation, add water to the sump.
  4. The media in the filter is easy to change. You can add larger quantities of charcoal, biological media, and maybe even other packets of quality water conditioners like Boyd’s Chemi Pure.
  5. A handy aquarist can build the sump himself. All you’d need is acrylic, acrylic glue, and a pump to push water back to the surface of the aquarium. People have made their own designs available on the Internet, accessible with a simple search. Of course, you could also just buy a pre-made sump.

wet-dry filter Starting a New Aquarium

This is a photo of the simplest of wet-dry filters. The water pours over the pre-filter sponge and then drips down through the plastic fiber underneath. Both the sponge and the plastic fiber serve as a bio-filter. The pump that pushes the water back to the tanks is placed in the left corner of the open area of the tilter. Any type of other filtration media can be placed into the filter under the pre-filter sponge. Remember not to use tap water to clean the pre-filter sponge. Use water from the aquarium to rinse the sponge. That preserves the bio-filter bacteria.

Each fish species has their own needs. When you buy a fish, learn about the species. Ask questions of a professional or read up on their practical care. Starting a home aquarium isn’t a difficult task, but it does require a little bit of patience and precision.

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