What is periphyton?

What is called periphyton? What is its role in aquatic ecosystems? Why is it essential in low-tech fishkeeping? How does it help balance a natural aquarium?

 

 

Periphyton, a harsh word but a simple reality.

The Aquazolla ZollaBox Starter is based on the principle of microbial biodiversity, and it contains elements of periphyton.
But why?

When you observe an aquatic ecosystem, whether marine or freshwater, you notice that all surfaces are covered with something. Whether that something is green, slippery, transparent, rough, or even black and unpleasant, it is what we call periphyton.

 

This layer that settles on everything immersed in a body of water begins as a simple biofilm. After a few days of immersion, a tiny layer forms mainly made up of bacteria, but also other microorganisms. It is initially invisible. Then, after a few months, the surface begins to look "dirty." It turns green, brown, black, not always evenly. The biofilm then receives algae, brown or green, which take a little longer to develop than the initial bacteria. These algae then allow tiny animals to feed, and they settle there.

Ostracods, for example, come to "graze" on this periphyton. They lay egg plates there which, once hatched, remain as a "crust" that in turn provides a foothold for other forms of life.
Snails absolutely need it to live and feed. Your bladder snails feed on it, as do all other snails. Water lice need it the most as well.

As you can see, periphyton is a deposit in successive layers, of living (biological) origin, that covers all submerged surfaces. Even the leaves of plants, if they last long enough, quickly become covered.

In short, periphyton is this layer that aquatic life forms on everything in the water.

 

What is its use in a natural aquarium?

In the past, people sought to have aquariums as "clean" as possible. I saw a lady who washed her aquarium every month and rinsed it with bleach. The result was the systematic death of fish and plants, a totally unstable aquarium, because no microbial biodiversity could establish itself.

Periphyton is a "biological stock." It contains everything traditional fishkeeping hated! Algae, bacteria, viruses, fungi, cyanobacteria, eggs of very diverse microfauna, lime deposits, etc. All this diversity means that no species manages to dominate the others, unlike what could happen in a "clean," new, and therefore barren environment.

 

Periphyton and the nitrogen cycle

The cycling of an aquarium, that famous start-up of the nitrogen cycle, is an example of the establishment of bacterial colonies. As long as the aquarium is a bacterial desert, nothing works.

The nitrogen cycle, in an aquatic ecosystem, is perfectly ensured by periphyton. It contains the bacterial colonies that ensure this vital cycle, but also many others.

A new aquarium does not yet have periphyton and must build it up.

It is clean, sterile, barren, and therefore dead.

Can this process be sped up? Can it be seeded directly?

Well yes!

This is the principle on which the ZollaBox Starter is designed.

It contains an extremely rich microbiota, derived from phytoplankton, zooplankton (microfauna), and even directly from periphyton. This periphyton, over 10 years old, taken from cultures never interrupted, is a true collection of diverse species. A library of all the forms of life that have succeeded each other in this old ecosystem.

Introducing this periphyton immediately establishes an extremely rich biodiversity, without having to wait years.

Aquariums without filters

It is periphyton that ensures, in nature, the biological role that we traditionally entrust to the filter. This is why an aquarium actually does not need a filter, since the periphyton that performs all its functions (and many more) is installed on all the aquarium supports. Every grain of sand, over time, is coated by this periphyton, bacteria are everywhere, and those in the filter are even in the minority!

This is why, when you remove the filter, nothing special happens.

It is periphyton that explains why an aquarium becomes more stable over time. The balance of the aquarium rests on periphyton and depends on its complexity. The older the periphyton, the more complex and diverse it is, the more stable the ecosystem: shocks are smoothed, cushioned, absorbed by its diversity, in which there is always the species the environment needs to avoid extremes.

Periphyton and trashcan ponds

The trashcan pond, that container placed outside to house fish in summer or create a small planted aquatic ecosystem, is also a place where periphyton forms. It is outside, exposed to all the dust carried by the wind, and so it acquires a multitude of microscopic species brought by air or rain much faster.

This periphyton becomes rich, and it is an excellent reason not to empty it in winter.

Season after season, its walls become covered with this living layer, sometimes crusted, which one wants to brush off to start "clean" for a new season!

On the contrary... You must leave the trashcan pond full in winter. Over the years, you will build a rich and complex periphyton.

To start your aquariums, you can scrape these walls to collect some of this periphyton and seed your aquariums with it.

It is the best way to give life to the water.

I just found the article I wrote more than two years ago on the Natural Aquarium blog.

It was here:   https://aquariumnaturel.blogspot.com/2023/03/quest-ce-que-le-periphyton.html
It was probably one of the first times the subject was addressed in fishkeeping, but I think it will be more and more so.