Wildscapes Feature

Building a
Living Ecosystem

A year of watching a small home pond transform into a thriving freshwater ecosystem.

9-minute read By Parag Kokane Freshwater Ecology · Urban Nature · Aquatic Life · Natural History

The small home pond surrounded by terrestrial and aquatic plants. Over time, the water, roots, rocks and sheltered spaces began supporting a much wider living community. Photograph by Parag Kokane.

I had arranged the rocks, water and plants.
The ecosystem that followed was shaped by life itself.

About a year ago, I set up a small 50-gallon tub pond at home with a simple question in mind: could a healthy aquatic ecosystem remain stable with very little intervention?

I did not want to create a decorative container that depended on constant cleaning, frequent water changes and regular adjustments. I wanted to create the basic conditions found in a natural water body—substrate, rocks, plants, shade, shelter, gentle water movement and animals occupying different parts of the habitat.

Once those elements were in place, I hoped the pond would begin doing some of its own work.

Over the following months, that is exactly what happened. Plants spread, algae appeared, fishes settled into different levels of the water, shrimps reproduced and snails became part of the cleanup cycle. In another old aquarium beside it, a population of tiny organisms appeared without being deliberately introduced.

The most interesting part was not that the setup survived. It was watching how many small ecological relationships developed inside such a limited space.

Beginning with the Bottom

The foundation of the pond was a layer of gravel and sand. I also added pieces of red laterite rock—Jambha Dagad collected from Konkan—and a couple of pieces of driftwood.

These were not only decorative. The uneven surfaces created many small spaces where algae, microorganisms and beneficial bacteria could grow. The driftwood and rocks also provided shelter for shrimps, loaches and other bottom-dwelling animals.

In an aquatic ecosystem, much of the important activity happens on surfaces that we hardly notice. Bacteria and other microscopic organisms break down organic matter and help return nutrients to the system. Gravel, wood, plant roots and rocks together create a much larger living surface than the open water alone.

Plants as the Working Structure

I planted several aquatic species, including different Anubias, Java Fern, Trident Fern, Cabomba and Elodea. Duckweed covered parts of the surface, while a potted water lily gradually produced broad floating leaves.

These leaves created shade and reduced the amount of open water exposed to direct sunlight. They also gave young fishes and shrimps places to remain hidden.

I added Peace Lily and Money Plant from my garden with their roots underwater and their leaves growing outside the pond. Their long root systems formed dense underwater tangles while drawing dissolved nutrients from the water.

The plants became much more than decoration. They provided shelter, grazing surfaces, shade and spawning cover. They also became one of the main ways in which nutrients were taken back out of the water and converted into new growth.

The pond after nearly a year of growth. Beneath the visible plants and fishes, a much larger community had gradually established itself. Video by Parag Kokane.

Tiny oxygen bubbles collecting on aquatic plants during active photosynthesis. This visible release is often called “pearling” in aquarium keeping. Video by Parag Kokane.

Life at Different Levels

While selecting fishes, I tried to avoid filling every part of the pond with animals competing for exactly the same space.

Platies, guppies and killifish remained mostly near the upper levels, where floating plants and insects offered cover and food. Harlequin Rasboras occupied the middle water. Near the bottom were Panda Corydoras, Kuhli Loaches, a Golden Algae Eater and a Siamese Algae Eater.

This did not turn the pond into a perfect copy of a natural freshwater habitat—the species come from different parts of the world—but it did create a layered community. Different animals searched for food, rested and sheltered in different parts of the water column.

A double-layer cascading waterfall, powered by a canister filter, circulated the water gently and increased surface movement. This meant the pond was low-maintenance rather than completely without filtration, but the biological work was being shared by the plants, substrate and living community rather than depending only on equipment.

The Shrimps Begin to Multiply

Red Cherry Shrimps and Yellow Golden Back Shrimps were among the smallest animals I introduced, but they soon became some of the most visible signs that the habitat was functioning.

The yellow shrimps arrived when they were less than a centimetre long. As they grew, their colour became striking against the dark plants, wood and gravel. The red shrimps also began reproducing, with females carrying clusters of eggs beneath their bodies.

Young shrimps are vulnerable in a pond containing fishes. Many would naturally be eaten, but dense vegetation and root cover allowed enough of them to remain hidden and survive. Predation prevented unrestricted population growth, while shelter ensured that the shrimps did not disappear completely.

The shrimps grazed continuously on algae, biofilm and decomposing material. When organic matter reached the bottom, it did not remain untouched for long. Shrimps, snails, fishes and microorganisms all participated in breaking it down.

A berried Red Cherry Shrimp carrying developing eggs beneath its abdomen. Video by Parag Kokane.

Another close view of a female Cherry Shrimp carrying eggs, surrounded by the fine growth and plant cover of the nursery tank. Video by Parag Kokane.

A Nursery Without Fishes

While developing the pond, I also converted an old aquarium into a shrimp nursery. I began with only four Red Cherry Shrimps.

Within a few months, the aquarium held shrimps of almost every size—tiny newly hatched young, medium-sized juveniles and fully grown adults. I eventually moved the larger adults into the pond because the nursery population was increasing rapidly.

The aquarium had no fishes, no air pump and no regular feeding. It also had no conventional filter. Plants, algae, biofilm and decomposing organic material supported the shrimps, while the absence of fishes allowed many smaller organisms to remain visible.

I would sometimes sit beside the tank and watch this miniature world at close range. It was here that I noticed an organism I remembered from school science books.

Hydra in the Tank

Attached to the glass and plants were tiny freshwater hydra. Their narrow bodies were easy to overlook, but under close observation their tentacles could be seen moving slowly through the water.

Hydra are small freshwater animals related to jellyfish and sea anemones. They attach themselves to a surface and use their tentacles to capture minute prey drifting within reach.

In a fish aquarium, they may remain unnoticed or be eaten. In this fish-free nursery, they had enough undisturbed space to become part of the visible community.

Their appearance was a reminder that the shrimps were only the most obvious residents. The tank also contained microscopic life, tiny invertebrates and food-web relationships that could not be understood simply by counting the animals I had introduced.

Hydra can capture extremely small aquatic organisms and may prey on newly hatched shrimp under some conditions. I did not observe an obvious problem in this tank, but their presence showed that even a small nursery could develop its own predators as well as grazers and decomposers.

A female Yellow Golden Back Shrimp carrying eggs beneath her abdomen. Successful breeding showed that the planted habitat offered sufficient food and shelter. Photograph by Parag Kokane.

A freshwater hydra extending its tentacles inside the shrimp nursery—an easily overlooked predator within the developing food web. Video by Parag Kokane.

The Useful Work of Snails

Three kinds of snails were present in the pond: Nerite Snails, Assassin Snails and the small snails often described by aquarium keepers simply as pest snails.

The name “pest” depends largely on perspective. These small snails grazed on algae and decomposing material. Their numbers could increase quickly when excess food was available, but they were also prey for the Assassin Snails.

This created another small relationship within the pond. One species helped process organic material, while another prevented it from multiplying without limit.

Such relationships are never perfectly controlled. Populations rise and fall depending on available food, shelter, predation and changing water conditions. Stability does not mean that everything remains constant. It means that change can occur without the entire system immediately collapsing.

What “Self-Sustaining” Really Means

It would be misleading to describe the pond as completely independent. I selected the container, added the substrate, introduced plants and animals, installed water circulation and topped up water lost through evaporation.

I also continued watching it. Observation is part of responsible care. A small artificial pond cannot absorb every imbalance in the way a large natural wetland might.

Yet after the initial setup, the pond required remarkably little intervention. I did not perform routine water changes, and for long periods I added little or no supplementary food. Algae, insects, plant growth, biofilm and decomposing organic matter became part of the food supply.

Waste from one organism became material for another. Shrimps and snails grazed on surfaces. Microorganisms broke down organic matter. Plants absorbed dissolved nutrients. Fishes preyed on some of the young shrimps, while dense cover allowed others to survive.

The pond was therefore not a sealed ecosystem. It was an open, managed habitat in which natural processes carried much of the daily work.

Natural History

What Was Happening Inside the Pond?

The pond was not simply a collection of plants and animals. Several ecological processes were taking place at the same time, each supporting another part of the living system.

Biofilm formed on almost every submerged surface. Rocks, driftwood, gravel, plant leaves and roots became coated with microscopic communities of bacteria, algae and other organisms. This biofilm provided a constant grazing surface for shrimps, snails and some fishes.

Plants converted light into new life. Aquatic and emergent plants used sunlight, water and dissolved carbon dioxide to produce new growth. During active photosynthesis, some of the oxygen they released became visible as tiny bubbles.

Different animals used different parts of the habitat. Surface fishes searched for insects and food near floating plants, rasboras occupied the middle water, while loaches, corydoras, shrimps and snails remained closer to the substrate.

Predation helped regulate populations. Some young shrimps were eaten by fishes, Assassin Snails preyed on smaller snails, and hydra captured minute aquatic organisms. These interactions prevented every population from increasing without limit.

Dead material did not remain waste for long. Fallen leaves, animal waste and other organic matter were gradually consumed and broken down by shrimps, snails, microorganisms and bottom-dwelling animals.

Nutrients returned to the plants. Decomposition released nutrients back into the water and substrate. The roots of aquatic plants, Peace Lilies and Money Plants absorbed them and converted them into fresh leaves, stems and roots, completing another part of the cycle.

A Wildscape Close to Home

I usually think of a wildscape as a forest, river, grassland, mountain or coast. This pond was none of those things. It was a plastic tub placed at home and assembled by hand.

Yet the processes unfolding inside it were familiar: competition, shelter, grazing, predation, reproduction, decomposition and the constant movement of nutrients through living bodies.

The pond did not become natural simply because I stopped interfering with it. It became ecologically interesting because I created suitable conditions and then allowed enough time and space for relationships to develop.

What began as a small home project gradually changed the way I looked at the water in front of me. I no longer saw only the fishes and plants I had added. I saw a community—partly designed, partly spontaneous and always changing.

Sometimes the most revealing natural history observation does not require a distant forest or a rare animal. It begins by sitting quietly beside a small body of water and noticing who else has arrived.

About Parag Kokane

Parag Kokane is an observer of nature whose work combines field observation, natural history, wildlife photography and writing. Through Wildscapes, he explores the forests, freshwater ecosystems and everyday wildlife of the Western Ghats, sharing stories that encourage readers to look more closely at the natural world around them.