The Natural Aquarium: Looking To Native River Systems for Inspiration

I recently viewed a short film produced by National Geographic, which shows freshwater shrimp living in tropical streams. These streams in Puerto Rico have developed diverse populations of crustaceans in relatively small pools of water. These shrimp constantly feed on organic debris that collects in the pools, keeping them clean and clear. This results in bodies of water that are appealing to both animals and humans alike.

In the video, a researcher describes the unexpected complexity of life in small, stream-fed pools in Puerto Rico. He says there can be 10 species making up every niche in one of these pools. All of these species are a type of crustacean, shrimp, crabs, crayfish. Each species finds a specialty. The result is a balanced ecosystem which relies heavily on leaf litter as the base for nutrition entering the system.

It truly is fascinating, coming from the perspective of someone who’s goal in the aquarium hobby is to recreate a kind of nature-inspired habitat for invertebrates and fish. I regularly add dead and decaying leaves to my aquariums and pond to feed snails, shrimp, amphipods, and other too-small-to-see creatures that inhabit those environments. If it works for nature, there is no reason it can’t work for us.

Below you will find the video clip I refer to above.

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Sometimes we as hobbyists obsess over making our aquariums as pristine as possible. We never realize that in doing so we may be doing a great disservice to the animals we keep. This is especially true for those species which have evolved to scavenge on the substrate of their natural habitats. Shrimp, snails, and bottom-feeding fishes, all of these species constantly patrol the bottoms of streams and pools looking for food and shelter in the litter. There is also the health benefits animals receive from natural tannins usually found in this forest covered bodies of water.

I use very little mechanical filtration in my aquariums, to allow some of this detritus to accumulate for my pets to do what they are built to do. In addition, I don’t do any kind of chemical filtration. In the past I have had great success with small, 3 gallon or less, aquariums without any filtration at all. I now prefer to use miniature sponge filters to both aerate the water as well as keep a flow to distribute debris and nutrients evenly in the water. The benefit of the sponge itself is to allow more surface area for bacteria. Shrimp and snails also enjoy picking out bits of debris on the surface of the sponge for food.  I use organic soil substrate, lots of plants, and infrequent but regular water changes. Some would say that is impossible to maintain a healthy aquarium this way. I’ll admit it is not always easy. When a “natural aquarium” finds a balance and comes into its own, the result can be truly rewarding.

I’m not advocating for everyone to stop filtering or performing regular water changes. It is important to properly maintain the quality of water in our aquariums, for the the benefit of our beloved pets. I’m also not recommending that beginner hobbyists go without first understanding and mastering the basics to aquarium keeping. But I think as we progress as a group in this hobby, we should move away from the practice of over filtering, over dosing with chemicals, and manically replacing water multiple times a week. It seems the goal is to create an environment that just does not naturally occur. Nature is dirty, sometimes stinky, usually covered in something slimy, and always working towards balance. I say we stop trying to fight nature, and instead try to learn from it.

Cover photo credit: Mark Hanford

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