Interactive lesson

Pond fish species, step by step

Interactive lesson: carp, tench, grass carp and trout — which fish for which water, how many per 100 m², which fingerlings to buy and how to release them into the pond.

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The whole lesson as text

1. Choose fish by the water

Every fish has its water. You choose by the water, not by taste.

Carp for warm water — Still, warm (22–28 °C) and cloudy water in August: the main fish is carp. Don't put trout there. In North America the usual choice is catfish, or bluegill with bass.
Tench for mud — Tench live near the bottom and tolerate very little oxygen and warm mud. With a muddy bottom and little inflow, tench and crucian carp are the main fish.
Grass carp only with plants — Grass carp eat water plants the way a cow eats grass. A pond without plants doesn't need them.
Trout for cold water — Trout need cold, clear, running water, below 18 °C (64 °F) even in summer. Carp grow slowly in such water.

Why: Carp tolerate what would kill a trout within an hour. Put "a bit of everything" into a pond, and in autumn you net goldfish, pumpkinseed and a few thin carp.

Take the water measurements from H30-01: August temperature, flow, test pit. Choose the fish by them.
If you're not sure, start with carp and tench. They forgive mistakes that would kill a trout.

2. Carp

Carp are the backbone of a warm pond: they eat everything and root about on the bottom.

The main fish — They grow best between 20 and 28 °C. From fingerling to table carp of 1.5–2 kg (3–4½ lb) takes three summers; in the cooler UK and Irish summer allow a fourth.
Common or mirror — Common carp are fully scaled, hardy and the most common. Mirror and leather carp have a few large scales or none: easier to clean, slightly more delicate.
Sizes by summers — One-summer fingerlings weigh 20–50 g in autumn, two-summer fish 200–500 g. Table carp of 1.2–2 kg are for eating, not for stocking.
Two-summer fish in spring — For a first pond buy two-summer fish in March–April. By October they reach 1–1.5 kg and you harvest the same year. In the UK and Ireland plan on the lower figure.

Why: They eat worms, larvae, plankton, seeds and grain. They feed and grow from roughly 10 °C (50 °F); below 8 °C they barely feed and rest in deep water.

A carp of 1.5 kg has the best ratio of meat to bone. Under 1 kg it has the most fine bones per kilogram of meat.
Koi are the same species. Don't mix them with table fish without a health check.