June 28, 2025, 5:43 am | Read time: 7 minutes

A small water feature on the balcony or in the garden acts like a magnet—not just for the eyes, but also for insects, birds, and even fish. However, what seems simple requires more planning than one might think, especially when it comes to selecting plants and animals for the small pond.

Choosing the Location and Water Quality–A Delicate Balance in Mini Ponds

“Small or mini ponds are decorative and enliven gardens, terraces, and balconies. However, due to the relatively small water volume, there are a few things to consider,” explains Jonas Liebhauser, a pet expert at the Federal Association for Proper Nature, Animal, and Species Protection (BNA) in Hambrücken.

Because of the low water content, both temperature and oxygen levels can change quickly. Pollutants like ammonia also concentrate faster, which can be problematic, especially when keeping fish. A pond filter and regular water changes help maintain consistent quality. To avoid overheating in summer, a generally shadier location is recommended.

Suitable Containers for Mini Ponds–From Pond Basins to Wine Barrels

Various containers can be transformed into a mini-biotope–including wooden tubs, pond basins, or even mortar tubs. Ideally, a volume of at least 60 liters with a depth of at least 30 centimeters is optimal. Watertight containers simplify setup; otherwise, pond liner provides the necessary sealing.

If the pond is to remain outdoors permanently, the material must be frost-resistant and free from harmful emissions. Both built-in and freestanding variants are possible. To improve aesthetics, wooden cladding can be added. For those who prefer simplicity, ready-made complete sets, including technology, are available. Specialty stores offer individual advice.

Choosing Plants by Water Zone

In mini ponds, it’s important to use plants according to their water zone preferences. Water lilies (Nymphaeaceae sp.), for example, belong on the pond bottom, while a marsh marigold (Caltha palustris) prefers the shore zone. Many pond basins already offer integrated zones for marsh or shallow water, which only need to be planted. In other containers, lime-free stones or bricks help create different levels and plant zones.

Special plant baskets for ponds, such as those with pond soil or other nutrient-poor soil, are also helpful as they make planting easier. Fine-mesh jute fabric and a cover with smaller pebbles prevent pond soil from floating. If necessary, the plants can be easily removed with the basket–for example, if they need to be overwintered frost-free.

For the respective water zones, the following plants are suitable:

• Shore zone (0–5 cm): Marsh marigold (Caltha palustris), purple loosestrife (Lythrum salicaria)
• Marsh zone (5–15 cm): Bog arum (Calla palustris), marsh cinquefoil (Comarum palustre)
• Shallow water zone (15–50 cm): Water plantain (Alisma plantago-aquatica), pickerelweed (Pontederia cordata)
• Deep water zone (from 50 cm): Frogbit (Hydrocharis morsus-ranae), pygmy water lily (Nymphaea tetragona), common duckweed (Lemna minor)

All mentioned species are found in Europe, which makes care easier. Exotic plants, on the other hand, can spread uncontrollably and are potentially invasive. To avoid this, using native species is advisable.

Keeping Fish in Mini Ponds Is Only Practical in Summer!

Mini ponds provide food for fish–mosquito larvae are also part of their prey. However, year-round keeping is problematic. The water volume in mini ponds is too small to keep fish outside all year. The risk is too great that all the water will freeze in winter. Therefore, the animals should be housed in an aquarium during winter.

As with plants, species can survive and reproduce in nature. Therefore, it is essential to prevent the intentional or accidental release of non-native species.

Which Fish Are Suitable for Small Ponds

A small garden pond doesn’t have to be fish-free even without a pump. Certain fish species can manage with little oxygen and contribute to the biological balance. Native cold-water fish are particularly suitable for a mini pond. These include minnows, sunbleaks, bitterlings, and sticklebacks, as well as non-native species like pygmy sunfish or rainbow shiners. Important: Just because they are also called minnows, the latter should not be kept with native minnows, as they do not get along.

Suitable species for summer keeping include medakas (Oryzias latipes) or white cloud mountain minnows (Tanichthys albonubes). Medakas are comfortable up to 82 degrees Fahrenheit, while white clouds prefer up to 73 degrees. The minimum temperature for both is about 64 degrees. The lively guppies are also among the most popular mini pond inhabitants. They are characterized by bright colors and a high reproduction rate–ideal for quickly establishing a stable population. Guppies prefer higher temperatures and benefit from direct sunlight. Their diet of algae and insect larvae also helps keep the water clean.

For many, goldfish are the epitome of a garden pond–however, many recommend keeping them only in a larger pond. They do not require elaborate technology and can withstand temperatures between 41 and 86 degrees Fahrenheit without issue. As scavengers, they help keep the water clean by feeding on algae and dead plant material. Additionally, longear sunfish can be kept in mini ponds, as they prefer warmer water but can also tolerate lower oxygen levels. Their diet is varied: insects, small crustaceans, and other small animals are on the menu.

Paradise fish (Macropodus opercularis) are known for their intense coloration and lively behavior. The animals from Asia do well with moderate light and temperatures between 72 and 82 degrees Fahrenheit. As omnivores, they are easy to care for. Thanks to their striking, wavy tail fins, veil tails are also a decorative eye-catcher. The animals require little space and no special technical requirements, making them a popular choice for smaller ponds.

Care Requirements for Fish in Mini Ponds

The presented species can live in a mini pond in summer–but should not be mixed with each other. Each species has its specific requirements for water temperature and values. Therefore, especially in a mini pond, not too many fish should be introduced at once. As a guideline, one fish per 20 liters of water is recommended. For smaller ponds, keeping at most one to two small species is suitable. The ideal pond depth is between 35 and 70 centimeters.

The food must also be properly dosed. When feeding once a day, enough should be given so that the animals can eat it in five to ten minutes. The amount of food is calculated based on the number, weight, and type of fish, as well as water temperature. A rough formula is: Daily food amount = (number of fish × average weight × food requirement in %) / 100

Example: 10 goldfish at 50 g each with a 2% requirement: (10 × 50 × 2) / 100 = 10 g of food per day

A clean pond is essential. Therefore, regularly remove leaves and food residues. A partial water change of about 20% every two weeks helps reduce pollutants. Additionally, especially if fish are to live in the mini pond, plants can serve as natural filters. They improve water quality and provide oxygen. They also offer protection from the sun and predators.

In the mini pond, it is generally important to keep predators away and create retreats. Protect your fish best with nets or pond covers from predators. Regular monitoring helps detect behavioral changes and diseases early. Watch for changes in swimming behavior, fins, or coloration.

More on the topic

Keeping them in a terrarium How can you provide newts a species-appropriate home?

Cold Water Fish How to Keep and Care for Sticklebacks in an Aquarium or Garden Pond

"Mini Dinosaurs" of Pets How to Keep the Plumed Basilisk in a Rainforest Terrarium

Additional Benefits for Humans and Animals

A mini pond not only enhances visually but also offers additional benefits. Herbs like watercress and water mint can complement your diet. Additionally, birds and insects are provided with water during dry summers–an important contribution to the local wildlife.