Gudgeon

About

The gudgeon is a small, blunt-headed, barbel-cornered bottom fish that lives in shoals over clean sand and gravel, and in Lithuania it is one of the commonest fish in a running river — Lithuanian Wikipedia records it in clean fast rivers, the Kaunas Reservoir and the Curonian Lagoon, holding in groups in shallow water below the rapids. FishBase gives a maximum of 21 cm and a common length of 12 cm, with a maximum published weight of 220 g and a maximum age of eight years; Wikipedia says a typical fish is 9–13 cm and can live five years, while Lithuanian Wikipedia reports 10–15 cm as usual and 25 cm as the extreme. It is a real oddity acoustically: FishBase and Wikipedia both record that gudgeon emit squeaking sounds, and FishBase adds that these vocalisations vary with activity and temperature and are independent of the breeding season. Two facts decide whether it can live in your tank. FishBase's climate row reads 'Temperate; 2°C - 18°C' — this is a coldwater fish, and a heated tropical community will cook it slowly. And it is a shoaler that spends its whole life on the bottom of moving water: FishBase says it forms schools, Lithuanian Wikipedia says it holds in shoals in shallow water and never rises to the surface. One gudgeon in a warm tank is two mistakes, not one.

Care

Cold, moving water and a group — this is a pond or coldwater river tank, never a tropical one. Six or more, a soft sand bed they can work with their barbels, open swimming space over it, real current and strong aeration: reckon on 450 litres and 150 cm of length as the floor for a shoal — six fish that reach 21 cm and never leave the bottom need floor space, not just water, and no heater at all. FishBase's temperature band is 2–18 °C, so anything sustained above about 20 °C is the wrong home; an unheated room, a cellar tank, a chiller or a garden pond are the honest options. Keep the layout open rather than densely planted — Lithuanian Wikipedia says they prefer shallow sandy or gravelly places with little or no vegetation — and feed sinking food, because they do not come up. They will not damage growing plants; the only plant note in the sources is a mention of aquatic plants in the wild diet, alongside invertebrates and the eggs of other fish, and no source describes a gudgeon stripping a planted tank. Do not keep them with anything that eats a 12 cm fish. In Lithuania this is a native, unprotected species not listed on the country's protected species list, and it has no minimum size in the amateur fishing rules — but the general limits still apply, and releasing or moving wild animals is a separate matter. The Ministry of the Environment’s rules require advance notice to and approval from the Environmental Protection Department before translocating wild animals of any species or releasing wild mammals and birds, and a permit from the Environmental Protection Agency for introduction or reintroduction; where the act is a plain release into the wild of an animal that is not a bird or a mammal — a fish, in other words — the same rules instead oblige you to consult the Department, the Agency or a research institution first. Whichever branch a bucket of gudgeon falls under, it is not a decision to take alone. Rules elsewhere differ; check your own.

Diet

Bottom-feeding omnivore: insect larvae (especially chironomids), molluscs, crustaceans, worms, fish eggs and fry, with some plant material. Feed sinking foods — it never comes up to the surface.

Telling males from females

What works for this species, most reliable first.

• Belly depthA hint only · only on well-fed adults, and only as a comparison

  For most tetras, barbs and rasboras this is all there is: a conditioned female is deeper through the belly than a male of the same length.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

These links are unpaid: we get nothing for them and ask for nothing.

Frequently asked questions

What tank size does a Gudgeon need?

A Gudgeon needs an aquarium of at least 450 litres (118.9 US gallons) with a footprint at least 150 cm (59.1 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Gudgeon need?

Gudgeon does best at 2–18 °C (35.6–64.4 °F), pH 6.5–8 and a general hardness of 8–20 °dGH.

What group size does a Gudgeon need?

Gudgeon is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Gudgeon suitable for beginners?

Gudgeon is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Sources

• FishBase — Gobio gobio (Gudgeon)
• Wikipedia — Gobio gobio
• Vikipedija — Paprastasis gružlys
• Lietuvos raudonoji knyga — Lietuvos Respublikos saugomų gyvūnų, augalų ir grybų rūšių sąrašas 2020 m.
• Medžioklė ir žvejyba — Žvejybos taisyklės, leistini žuvų dydžiai (2026)
• Lietuvos Respublikos aplinkos ministerija — Keičiasi laukinių gyvūnų, augalų ir grybų rūšių introdukcijos, reintrodukcijos ir perkėlimo reikalavimai