Skip to Content

How to Look After Goldfish in a Pond: The Ultimate Guide

A goldfish swimming in a pond with lily pads and flowers.

Goldfish are a perennial favorite for anyone wishing to keep fish as pets. They are relatively inexpensive and hardy fish, fairly low maintenance, and require little fuss. They can be kept in a well-maintained aquarium indoors yet thrive with the freedom and space afforded by an outdoor pond.

Keeping goldfish in an outdoor pond is fairly easy and inexpensive. The straightforward setup includes proper feeding, cleaning the pond, and managing the good bacteria content in the pond, ensuring happy and healthy goldfish that will live and thrive for years to come.

With proper pond management, goldfish will flourish in an outdoor pond all year round. Depending on the pond size, goldfish come in a multitude of colors and sizes and can live up to a venerable old age of 30 years. Check this ultimate guide on caring for goldfish and ensuring they are given the best chance of a long and happy life.

Goldfish Types: Outdoor Pond Variety

The goldfish (Carassius auratus) is a wonderful species of freshwater carp that comes in well over 200 varieties through centuries of selective breeding, with many of them compatible with an outdoor pond. They were first bred for their exotic colors in China well over 1000 years ago and are a common feature in many parks and public ponds worldwide.

There are principally two groups of goldfish: one suited to indoor aquariums only and another that can be kept in outdoor ponds all year round. Some of the best varieties for an outdoor pond environment include:

Note: This post may contain affiliate links which will take you to online retailers that sell products and services. If you click on one and buy something, I may earn from qualifying purchases. See my Affiliate Disclosure for more details.

FUN FACT: Many of these goldfish come in a range of colors, growing up to 14 inches and with a life expectancy of well over 25 years in some, given the right controlled habitat.

Large goldfish swimming in a pond with lily pads.
Goldfish come in many varieties, get the right type for an outdoor pond

Outdoor Pond Goldfish: Important Considerations

Finding an occasional fish floating and lifeless in your goldfish pond is no cause for alarm. Goldfish, as tough as they are, are also susceptible to illness, old age, or stress-related death, much like their free-roaming cousins in the wild.

However, if your precious pet fish are starting to die off in numbers, it may be due to several reasons, and good cause for quick intervention to prevent further fish loss.

Oxygen-Related Pond Issues

One of the goldfish’s most important life-sustaining factors is sufficient dissolved oxygen supply. Photosynthesis, the natural process where aquatic plants and algae produce oxygen in water, is responsible for sustaining the oxygen supply needed to keep the fish alive.

Another lesser-known factor contributing to the oxygen supply is diffusion from the atmosphere, especially by the wind that causes turbulence on the water surface and induces oxygenated water necessary for animal and plant sustenance.

At night, aquatic plants, animals, and the decomposition of organic material all consume oxygen which needs to be replenished. If this consumption outstrips the oxygen generated, the depleted supply can cause fish kills.

NOTE: If your larger fish start dying off or are observed gulping for air at the surface, your oxygen levels may be too low.

Health Risks For Goldfish in the Summer

Excessive vegetation, where 80% of the surface is covered by plants, can cause oxygen depletion. This happens especially in periods of hot, humid, windless weather. The heat mitigates oxygen dissolving in the water. Cloudy days prevent adequate photosynthesis. A lack of wind inhibits water turbulence needed to diffuse oxygen into the water.

A pond covered with green plants and a flower.
Excessive pond plants can deplete water oxygen

Pond owners sometimes treat the pond with excessive amounts of herbicide or algaecide to try to control excessive plant growth. This can cause the bacteria produced by the massive plant to die off to consume the oxygen too quickly, causing a dangerous depletion of oxygen and harming the fish.

The same effect occurs as phytoplankton tends to die off naturally during extended periods of cloudy, windless, and hot weather. The color of the water can abruptly change to clear or black, and the goldfish will start to struggle for oxygen due to the increase in plant-eating bacteria.

Health Risks For Goldfish in the Winter

Winter fish deaths are not very much of a problem except in extremely cold areas, especially in the northern high elevation parts that receive excessive amounts of snow or ice. Low water temperatures inhibit plant growth, so if this occurs for extended periods, low rates of photosynthesis can reduce the amount of oxygen produced.

Routine Maintenance Required For a Healthy Pond

Looking after your goldfish pond is not difficult. However, it requires you to pay attention to a few fundamental rules to ensure that your pond is a healthy home for your goldfish.

#1. Limit Plant Growth

Goldfish do best in water temperatures between 65 and 85 degrees Fahrenheit. Ensure your plant cover does not exceed 75% of the pond surface. This will keep the water temperature at optimum levels.

#2. Install a Suitable Filtration System

Inadequate filtering is a major cause of too much ammonia and nitrates in pond water, both toxic to fish. This process occurs due to the build-up of fish waste and the decomposition of plant material.

IMPORTANT TIP: Test the water and check or clean your filter regularly.

#3. Do Not Keep Too Many Goldfish

Too many fish in your pond will also cause excessive waste and a build-up of nitrates. A single average-sized goldfish requires around 3 to 4 square feet of surface water.

A pond with many goldfish.
Too many fish in a pond will cause problems

#4. Clean The Pond Regularly

Skim debris such as leaves and clean the pond often. Decomposed organic matter provides a food source for unwanted algae, which consumes oxygen. It also makes the pond look unattractive.

#5. Feed With The Correct Food

According to the product instructions, feed the fish with food specifically designed for goldfish. Do not overfeed. Excess food not consumed contributes to waste contamination.

#6. Fertilize According to Guidelines

Proper plant management is critical for goldfish survival. They protect them from predators and direct sunlight. Use fertilizer according to specific plant guidelines to ensure healthy plant growth.

#7. Keep Water Levels Constant

During hot summer periods, water evaporates from the pond. Check the pond’s water level and top up regularly with dechlorinated fresh tap water to maintain healthy levels.

#8. Winter Maintenance

Winter maintenance should be easy, depending on the type of goldfish you have. Comets, for example, require warmer water but the Wakin variety are happy outside.

Turn off the filtration system and move the plants to the deepest part of the pond. The goldfish will go into a hibernation state at the bottom of the pool. Do not feed during the winter months. Goldfish that do not tolerate the cold should be brought indoors and stored in an appropriate indoor environment.

NOTE: If the pond surface freezes solid, bring your goldfish indoors and make a hole in the ice cap to allow gasses to escape.

A goldfish with its face out of the surface water.
Keep your goldfish happy and healthy for a long life!


Bad water quality is a leading cause of goldfish deaths in ponds. Many people who own fishponds unintentionally neglect their ponds and allow them to deteriorate to a state that eventually kills off the fish.

With a few simple rules and good habits, it is possible to keep goldfish looking beautifully healthy and happy for years, making them an ultimate investment in natural beauty.

Interested in learning more about fish? Read these articles: