The Ecology of the Aquarium – And How It Led Me to Permaculture

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“…my fish tanks were essentially wastelands!”

I have had an aquarium (or two) in continuous operation since 2004 – a large goldfish tank and a small betta tank. However, between 2004 and 2010, my aquariums were really “fish tanks” by advanced aquarium hobbyists’ standards – meaning that they were focused on fish, with an artificial, decorative environment. Plastic and silk plants, plastic gravel substrate, and heavy mechanical and chemical (activated carbon) filtration were all in play in my tanks, even if I did use the occasional decorative natural stone or gravel. The “artificial, decorative environment” is a very common setup that is condoned by pet stores, aquarium stores, common knowledge and popular culture.

Goldfish aquarium

About the closest I got to an “ecology” in my fish tanks was to utilize – as all aquariums and fish tanks do – biological filtration via nitrogen-cycling bacteria as part of my filtration system (converting harmful ammonia from the fish’s waste to less-harmful nitrate). Also, various volunteer species of algae would spontaneously appear over the years, which I usually scrubbed off the glass and fake plants in order to keep the tank “clean.” These fish tanks were fairly high-maintenance, in that they required weekly water changes, monthly algae eradication, and frequent cleaning of the filter media and moving parts – all standard recommendations for aquarium maintenance. But from an ecological and biodiversity standpoint, my fish tanks were essentially wastelands!   

Betta aquarium

In mid-2010, both of my tanks suddenly became infested with dark brown algae, which out-competed all the green algae species and which covered everything, including the glass. Knowing that algae is a type of plant and helps keep water clean and oxygenated by photosynthesis, this was more of a nuisance than anything, since it completely blocked out the view of the tank. However, I knew a sudden change of this magnitude must indicate something wrong with business as usual. Water testing showed high nitrate in both tanks (especially in my goldfish tank, goldfish being heavy waste-producers). Why I was having a nitrate spike in both tanks all of a sudden, I’m not sure – but the municipal water in my city was, after all, notorious for having high nitrate levels because of agricultural runoff. I began to fight the brown algae with chemicals, but that only helped so much and for so long, and in days the stuff would come right back. At that point, I knew I had to take a different approach to both get rid of the stubborn algae and to lessen my maintenance work – I began to research replacing the fake plants with real plants, which would naturally clear up the algae by taking up the excess nitrates, thus depriving the algae of its nutrient source.

Changing to live plants and improving the artificial lighting in order to support them made a huge difference in the ecological balance of each tank. It wasn’t long before the brown algae disappeared in both tanks. One accident of the live plants is that with them, I introduced a few species of pond snails into the goldfish tank. Most aquarists consider pond snails a nuisance and try to eradicate them with poisons, but I let them happily proliferate, and when their population balanced itself, between snails and plants any excess algae was kept in check.

However, soon new species of green algae and cyanobacteria (also known as “blue-green algae”) began to bloom in my little betta tank. There was too much artificial lighting for such a small tank. So I set about a new approach to getting the algae back in balance: algae-eating animals. I first considered a tiny species of algae-eating catfish, but realized that it would increase the bioload (a term for the amount of animal life in an aquarium), thus increasing my water-changing maintenance. I settled on algae-eating freshwater dwarf shrimp – which produce far less waste than fish – and added a few to my betta tank. As it turned out, the shrimp only liked to eat certain species of algae, which let long, stringy hair algae and cyanobacteria quickly grow over everything in a thick mat, choking the plants! Noticing the drastic difference in algae species and amounts between my two tanks, I finally moved two pond snails from the large goldfish tank to the small betta tank. Within a couple of weeks, the two snails, along with the passel of young they produced, happily feasted on and thereby eliminated all the hair algae and cyanobacteria, growing to enormous size in the process.

Amano shrimp

From this I learned to embrace not just the beneficial nitrogen-cycling bacteria present in any healthy aquarium, but also to value the important roles that invertebrates, and especially plants (both leafy and algae) play in the ecological balance of the aquarium. The more I embraced this notion by adding more and more plants and exchanging my chemical filtration for more biological filter media for the nitrogen-cycling bacteria, the more I noticed my maintenance needs decrease and the nitrogen cycle in both aquariums become more stable.

After my betta passed away, I kept the little tank running for the one dwarf shrimp that was left. Decreasing the bioload in this tank effectively decreased the maintenance I have to do for this tank to merely topping off the water as needed, adding the occasional fertilizer for the plants, and very rarely performing a partial water change. It is very nearly a self-regulating system.

I really had an “a-ha” moment during the overzealous-brown-algae episode: that mimicking a natural system with all of its plant and animal life just made a whole lot more sense than the plastic plant-decorated, relatively barren fish tanks I was running before. Of course – with all elements in the right proportions – an aquarium based on nature would be balanced and take care of itself, just like a natural ecosystem would. But if this idea made so much sense, why weren’t more aquarists following it? The funny thing is, there is even a sense of fear among amateur aquarists of freshwater aquariums and live plants. Live plants are often said to be “hard to maintain” and “not for beginners,” while I actually found it to be much less work and worry to maintain an aquarium with live plants!

Planted goldfish aquarium

The transformation of my aquariums was a great introduction to ecology, and sparked a quest for more knowledge – not just about how to run a low-maintenance, natural aquarium, but about how to do other things in my life more simply and naturally. Around the same time in mid-2010 that I was rehabilitating my aquariums with live plants and invertebrates, I first stumbled across permaculture in my travels around the Internet. I was becoming interested in and searching for information on growing one’s own food and the idea of edible landscaping.  Like the idea of the low-maintenance, nature-based aquarium, here was another concept – permaculture – that just naturally made sense, because similarly, the idea is to observe and work with nature rather than against it, acknowledging the way ecosystems already work, persist and adapt on this planet without any outside inputs.

My experience with learning about designing and maintaining a balance of plants, animals and bacteria that mimics nature in the aquarium was also a good introduction to some of the principles of permaculture, unbeknownst to me at the time (here I am using the principles put forth by David Holmgren in his 2002 book, Permaculture: Principles and Pathways Beyond Sustainability):

  • Observe and interact – Observing a major change in the normal balance of my fish tanks (brown algae), I took it as a sign – like the appearance of a particular weed in a garden – that the ecology in the tanks was out of balance, and that the system was compensating with brown algae in an attempt to correct itself. I then interacted with the system to try to regain balance, experimenting first with algaecides, and then with the more natural solution of adding the plants and invertebrate animals that were actually missing from the system in the first place.  Observing that the large goldfish tank’s water chemistry and temperature was easier to keep stable than my small betta tank, I also tried upgrading my goldfish to an even larger aquarium – larger volumes of water being better able to maintain a more stable chemistry – which also improved the goldfish’s system as a whole.
  • Apply self-regulation and accept feedback – The freshwater aquarium is a microcosm of a natural freshwater ecosystem. Any problems I have with my aquariums are indications that I have not fully understood the ecology of such systems, and I am constantly learning and adjusting the way I set up and care for my tanks. I got a great example of feedback on the change to live plants from my betta. Bettas live in shallow pools and rice fields in the wild, and like to “lie down” and rest on water plants from time to time. Before the live plants, my betta had the best, softest silk fake plant I could find in town, and yet he never perched on it, and even shied away in apparent disgust whenever his fins barely touched it. He knew it was unnatural, and was having none of it! However, when I planted live plants in his tank, he would happily nestle down in them all the time – and by his more natural behavior, I knew I had done something right.
  • Integrate rather than segregate – No organism in the natural world lives in a vacuum, and the way we often structure a “fish tank” as such by segregating out one element of a system – the fish – is unnatural, ignoring the functions performed by the myriad of other species and elements in a healthy natural ecosystem. We amateur fishkeepers often think (and are told) that the only other thing that is necessary for a functioning aquarium setup is the bacteria that convert ammonia to nitrate. As a result, all of the functions that would be performed by other organisms in the natural system (oxygenation by plants and moving water; water purification by uptake of nitrate, minerals and chemicals by plants; uptake of solid waste by invertebrates and bottom-feeding fish) have to be performed by artificial inputs and the human fishkeeper – making for frequent, time-consuming, and energy- and money-intensive maintenance needs.
  • Use small and slow solutions – Instead of beating back a problem with a heavy-handed, fast-acting (but ultimately short-lived) solution that oversimplifies the problem (i.e. using algaecides), I learned to turn to nature for guidance and use a slower-acting, but long-term solution. Just as Holmgren’s symbol for this principle is the snail, so I utilized pond snails as my solution to keeping overzealous algae in balance over the long term.
  • Use and value diversity – When I planted my aquariums with live plants, I made sure to buy several different species, which would strengthen the system as a whole. Over the years, plant species that were initially dominant in my tanks have fallen back – but there is always another species to bloom up and fill its role. Likewise, I diversified my invertebrates by using three species of small snails and a different species of dwarf shrimp in each tank.

Having recently lost my goldfish in a cross-country move, I am now planning what’s next for my large aquarium. Currently, all that reside in it (besides some single-celled life) are plants and pond snails. I do not have a filter running on it, and yet the water remains crystal-clear and the nitrogen cycle is stable. Now, I want to take the ecological aquarium idea to the next level, creating an environment that more closely mimics nature, maintaining a natural aquatic beauty indoors with minimal energy use and intervention on my part. I plan to use the techniques put forth by well-known aquarist Diana Walstad in her book, The Ecology of the Planted Aquarium.

Natural Planted Aquariums more closely mimic a natural freshwater ecosystem by:

  • using a large number of live plants, far more than I currently have in my tanks
  • planting in a layer of soil instead of strictly gravel
  • stocking the tank with much smaller and fewer fish than are normally considered “acceptable” for a given water volume – in the wild, fish have far lower stocking rates than the way we humans tend to keep them
  • utilizing natural sunlight as the light source as much as possible

You can read more in a summary of Diana Walstad’s Natural Planted Aquarium setup.

Sarah Spotten currently lives in Colorado. As part of her PDC course she posted occasionally on topics related to the curriculum.

You can see other posts by Sarah here. You can read more about her current projects at http://sarahspotten.com.

7 thoughts on “The Ecology of the Aquarium – And How It Led Me to Permaculture”

  1. Thanks for this post–I seem to have run across a lot of these principles myself, when I found a leech this spring, realized I knew nothing about leeches, and took it home in a bottle of pond water to study it. From there, as I was cleaning trash out of the pond by throwing it into the bottom of my canoe, I began to discover that the hitchhikers on the trash were many and varied, fascinating little creatures everywhere! I began to bring some of the trash back to my home rather than throwing it away; then washing it off to collect the critters living on the inside and outside of pop bottles, aluminum cans, and on floating styrofoam.

    Tiny shrimp; copopods; snails; baby leeches; dragonfly and damselfly larvae; water-beetles! Everything I found has been fascinating, worthy of study, and everything seems to work together in the substrate of my “Odd Pond,” a 3-gallon tank sitting on a window-sill. I started early on to include duckweed, small plants that really like sunlight and that provide food and shelter for midsized to larger creatures. Then have been trying to raise some larger plants, not with great luck but still sticking with the theme of taking little ones from the pond (big pond, not hurting anything by harvesting).

    Then came a tadpole, shipped on accident from Florida to Wisconsin in a container of feeder goldfish. It needed to be adopted, so we took it in. Now I have a very tiny frog, who turned out to be a bullfrog. Notorious for spreading a fungus that kills all other amphibians, and too small to release into the wild at this time of year anyway, he/she fits right into the pond I randomly assembled in my jar in a window.

    Time to expand into a 10 gallon tank, and eventually there’s a 35-gallon tank to move into. The large tank will have not only the wee critters (leeches which eat little bugs instead of blood make awesome pets!!!), but also a terrestrial area for some philodendrons to grow, and a bullfrog to hide out in. I plan to put some of my rotten apple cores in a bin at the base of the tank, to raise fruit-flies until our frog outgrows them.

    It’s so fun!

  2. I have a 5 gallon jug I made into a self sustaining aquarium. It has a pair of guppies. 11 cherry red shrimp and one snail. It seems like giving the guppies some flake food once a week is the best balance so far.
    Today, I see two tiny snails….huh. can one snail bread with himself? Perhaps there were eggs on the plants?
    I love it so far and it has been about a month.
    I put sand in the bottom and gravel on top of that.
    Very good article. It makes me feel like I am on a good path.

  3. Great piece. I personally also did the same though I had a lot of plants die before I managed to get it right. In the end, I had to ask myself the question: what are some of the hardiest aquarium plants in the trade that will thrive with access to ambient light alone? That did the trick and now I have a lushly planted 4.75 gallon guppy tank stowed away in one of the darker corners of my bedroom!

  4. I actually am in this very process right now which is why I ran into this article. Currently adding even more plants and adding hiding spots for when I add dwarf shrimp. I am glad someone has tried this out before me so I know what to work towards. I love learning about each plant and animals needs and natural environment and trying to create a mini ecosystem that benefits every thing in the tank.

  5. Thank you for this perspective of patience and letting nature work.
    I’ve had tanks since 1968 and currently have a 65 gallon tank with 5 silver dollars, 3 catfish and an algae eater. We recently tried doubling the gravel in our tank on the advise of an “expert” whose tanks were pristine and he didn’t use filters.
    His system is to provide at least 4″ of gravel so an eco system developed that digests the nitrates and other chemicals.
    My tank developed a devastating diatom bloom that killed my lush plants and turned everything brown.
    Now I have a huge job clearing and cleaning out everything and changing half the water several times.
    I used to keep one inch gravel over under-gravel filters along with an external professional filter and changing 1/4 water every couple of weeks.
    I think I’ll return to my tried and true method.
    This is an article on how to cure these diatom blooms: http://jonospin.hubpages.com/hub/How-to-get-rid-of-Brown-algae-or-Diatoms-in-freshwater-aquaria

  6. Well, what can I say? Perfect as it sounds, like I reached the point after a few months of surfing the net and searching for possible answers and interrogating people as aquarists, and after all these I’m going back to the simplest answer source i could get, nature, and in this case rivers! Taking a piece of it would be enough and mixing it would be an art. Have it enjoyed.
    Thank you for writing this well the article.

  7. Thank you for this well written article Sarah. It is a treat for us to be able to join you in your thinking and discoveries.

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