Wildlife pond vs fish pond

# Wildlife pond vs fish pond

A wildlife pond and a fish pond are two different designs. One is for amphibians, invertebrates and plants, and is usually kept without fish. The other is for keeping fish, and needs the volume, filtration, pump and long-term care that job requires.

Trying to make one small pond do both jobs usually fails one of them.

This page is the design-difference chooser. Whether you may add fish to a pond already aimed at wildlife is answered in can I put fish in a wildlife pond?. How to build the wildlife version is in how to build a wildlife pond.

We have not tested products or ponds. The official points below are from the pages named, checked 14 November 2026.

What each pond is for

The RHS wildlife pond guide describes fish as top predators in a garden pond, reducing biodiversity. Froglife’s Just Add Water guide says the best wildlife ponds generally have no fish in them, because fish can quickly dominate a pond.

A fish pond is planned around the fish: enough volume, a way to keep the water suitable, and a routine you can keep up. Filtration and pumps are part of that conversation, which is why does a fish pond need a filter? is a different question from whether a wildlife pond needs the same kit.

If you want both, the usual honest answer is two ponds, not a compromise in one small hole.

Shape, depth and access

For a wildlife pond, the RHS asks for a long, shallow slope on at least one side, so animals can get in and out, and so a drop in water level leaves a damp edge rather than a cliff. It suggests a varied depth of about 20–60 cm (8 in–2 ft) to suit most of the plants and animals it has in mind.

Part of the pond should be in shade, to help with algae, and at least part should be in full sun, so the water can warm in spring for spawning. Autumn and winter are the RHS’s preferred time to make a new pond. Prefer rainwater; tap water should only be a last resort.

A fish pond still needs safe access for you, and a design the fish can actually live in, but a steep-sided formal pool with little shallows is a poor wildlife pond even if it looks tidy. A fish pond still needs a way for an animal, and for you, to get out if someone falls in; a sheer formal edge is a poor answer. Depth and volume for fish are a stocking and welfare question; do not copy the 20–60 cm wildlife band across and call it a fish pond.

Where the pond sits in the garden is a shared first step. Use where to site a garden pond before you decide which design you are digging.

Pumps, liners and day-to-day care

A wildlife pond is often run with plants, a shallow beach and no fish, and may not need the same mechanical kit as a stocked pond. A fish pond more often needs a pump and filter matched to the volume and the load, and safe electrics if anything is powered. Those details belong in the kit and safety guides, not in a single generic shopping list.

The liner or preformed shell has to fit the shape you actually want. A wildlife pond with a long beach is a different cut of liner from a steep-sided fish pool. Size it with the pond liner size guide once the outline is marked on the ground.

Unwanted fish do not go in the wild

If you already have goldfish, koi or other ornamental fish and you want a wildlife pond, rehome the fish or dig a second pond. The Environment Agency says ornamental fish such as goldfish and koi carp should be kept in garden ponds and not transferred into the wild, because of disease, parasites and the risk of interbreeding with threatened crucian carp. It also says that releasing fish into the wild, or moving them into fisheries, without Environment Agency consent is an offence under the Keeping and Introduction of Fish Regulations 2015.

Do not tip unwanted fish into a river, lake or local pond. Ask a reputable aquatic shop or a rehoming organisation about lawful options.

In England and Wales, keeping some non-native fish needs a licence. The GOV.UK rules on introducing or keeping non-native fish list species that do not need one, including goldfish and common carp. They also say grass carp and sturgeon can be kept without a licence in a garden pond that is a discrete body of water, no bigger than an acre, on private residential premises, with no risk of fish escaping into the wild.

Check the current guidance for the species you actually have. It covers England and Wales, so check separately in Scotland or Northern Ireland.

How to choose

• Want frogs, newts, insects and a planted, shallow-edged pond? Design a wildlife pond and keep fish out of it.
• Want to keep fish? Design a fish pond, with volume, care and any filtration or electrics planned before you buy the livestock.
• Want both? Plan two separate ponds, sited so they do not simply drain into each other.
• Inheriting a mixed pond? Do not move the fish into natural water. Decide which purpose the pond will serve, then rehome or redesign.

No purchase prices are listed here. Check the current price of liners, pumps or filters only after the design is settled, and only as a dated band from more than one maker if you come to compare products later.