When someone says “Aquarium”, the first thing that obviously comes to mind is a glass box with four walls filled to the brim with water that houses some form of aquatic fauna and flora. While that is, at the surface, accurate, there’s more to aquariums than meets the eye.
Aquariums are, when properly set up, are a microcosm of the wider global ecosystems found in nature. These so-called glass boxes give us a glimpse of the interdependence of one organism with another in an effort to jointly survive not just as individuals, but as entire species.
There is no single correct way to set up an aquarium (but there is absolutely an incorrect way, which we will discuss in a future post), but in my experience, the one that involves plants usually makes life easier in the long term. This is because this kind of setup emulates nature, which furthers my earlier point of interdependence amongst species within a closed system.
If we remember our fifth-grade lesson on the nitrogen cycle (quick refresher by one of my most trusted fishkeeping YouTube channels, Aquarium Co-op, here), we know that decomposing matter (i.e. fish poop, uneaten food, dead animals, other organic materials) produces ammonia, which is lethal to fish. However, bacteria naturally present in the water consume ammonia and convert it into nitrite first (still lethal to fish) and eventually nitrate (harmless to fish up to certain concentrations).
Fishkeepers are taught that to remove nitrates, they must perform weekly water changes. The percentage of water that we remove depends on specific tank conditions, but it’s usually up to 50% at a time. Effective, but water changes are tedious work, especially if you have more than 10 aquariums like me.
The good news is that plants consume nitrates — they are a natural fertilizer. Therein lies the interdependence I speak of. The fish provide the plants a source of nutrients via their feces and food scraps, while plants ensure that water quality doesn’t degrade to a point that’s detrimental to the fish.
Interdependence among species is not the only aspect of nature that’s reflected on a smaller scale in an aquarium. The interaction of flora and fauna with their environment, and how imbalances can cause the breakdown of a closed system, of which our planet and aquariums are examples.
Besides the nitrates in the water, another factor plants need to survive is light. Without light, plants cannot photosynthesize. In aquariums, we replicate this with full-spectrum LED lights. Leaving the light on for too long, or if the light you bought is rated too strongly for your specific tank, however, will lead to all kinds of algal bloom. Too little light will obviously lead to poor plant growth.
This cascades further to a point where fish can be affected. An algal bloom could choke a body of water, as algae consume oxygen, leaving little to no oxygen for fish. Algae can also block light from penetrating the water column, leaving underwater plants to struggle to photosynthesize.
All these scenarios happen in nature, and they happen in aquariums too. The next time you see an aquarium, don’t think that it is just a glass box. There is so much more going on inside, both seen and unseen. And remember that this is but a small snapshot of our greater world. Whatever lessons we might learn in fishkeeping can be applied to our efforts to make mother Earth a little bit better.
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