Grass Carp

About

The grass carp is a plant-eating machine sold as a solution. It is stocked in ponds across Lithuania and Europe precisely because it clears vegetation, and it does the job with a thoroughness people rarely plan for: Maidenhead Aquatics puts intake at up to three times the fish's own body weight of freshwater vegetation daily, and USGS cites a figure of up to 27.6 kg of vegetation per kilogram of fish per year. FishBase gives 150 cm total length and 45 kg, Maidenhead 120 cm with wild fish known at 1.5 m and 45 kg, and both agree it grows fast — a 20 cm spring fingerling passes 45 cm by autumn. It lives about twenty years, tolerates water from near freezing to the mid-thirties, survives months under ice and copes with dissolved oxygen down to 0.5 ppm. None of that makes it an aquarium fish. It is a large, nervous, jumping cyprinid that needs a pond, and it will eat any planting you put in front of it. The Lithuanian trade name — baltasis amūras — comes from the Amur river on the Russian-Chinese border, which is where it is actually from.

Care

Pond only, and a pond where planting is not the point. Reckon on at least 15,000 litres, four and a half metres of length and a cover over any low edge — Maidenhead notes grass carp are nervous and readily jump. Maidenhead gives 4-30 °C and FishBase records tolerance from near freezing to the mid-thirties, so no heater and no chiller; neutral to slightly alkaline, hardness up to 25 degrees, and filtration only needs to keep up with the waste — but the waste is considerable. Keep two or three rather than one; they are entirely peaceful with other fish and with each other. Do not put one in a planted pond you want to keep: a Lithuanian pond guide says small grass carp eat only beetles and soft young growth, but large ones can clear a water body of almost all aquatic plants, and Lithuanian Wikipedia warns that unless they are fed extra, they can destroy every plant in the pond. Legality depends entirely on where you are, and here the answer really does flip. In the European Union the instrument is Regulation (EU) No 1143/2014, whose Union list of invasive alien species runs to 114 species; grass carp is not one of them, and neither is it on Lithuania's separate national invasive list, which carries four fish — the round goby, the Amur sleeper, the monkey goby and the topmouth gudgeon. The Lithuanian pond trade accordingly sells it as one of five routine stocking species. That is what the market does, not what the law permits, and the two are not the same thing here. It is still an alien species in Lithuania, and the Ministry of the Environment states that the Law on Wildlife prohibits releasing or translocating alien-species animals into the wild — so a pond it can escape from is a legal problem and not only an ecological one. Cross to the United States and it is restricted state by state: Pennsylvania's regulation describes 'the prohibition of grass carp in this Commonwealth' and allows only USFWS-certified triploid — sterile — fish, under an $85 possession and introduction permit, while triploid stock is used for weed control in many other states. Check the rule where you actually live; it will not be the same rule.

Diet

Obligate macrophyte feeder. Higher aquatic plants and submerged grasses first, detritus and invertebrates second; in a pond it is fed cut grass, green pellets or flake and lettuce. It eats up to three times its body weight in vegetation a day and will strip a planted pond.

Telling males from females

What works for this species, most reliable first.

• Breeding tuberclesStrong · only in breeding condition — they vanish out of season

  Goldfish and their cyprinid relatives grow small white bumps on the gill covers and leading pectoral rays when they come into breeding condition.

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 Grass Carp need?

A Grass Carp needs an aquarium of at least 15000 litres (3962.6 US gallons) with a footprint at least 450 cm (177.2 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Grass Carp need?

Grass Carp does best at 1–33 °C (33.8–91.4 °F), pH 6.5–8.5 and a general hardness of 5–25 °dGH.

What group size does a Grass Carp need?

Grass Carp is a social species — keep a group of at least 2 so natural behaviour emerges and stress stays low.

Is the Grass Carp suitable for beginners?

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

Sources

• FishBase — Ctenopharyngodon idella (Grass carp)
• Maidenhead Aquatics (Fishkeeper) — Grass Carp, Ctenopharyngodon idella
• USGS Nonindigenous Aquatic Species — Ctenopharyngodon idella (Grass Carp)
• Vikipedija — Baltasis amūras
• Wikipedia — Grass carp
• Wikipedia — List of invasive alien species of Union concern
• LR aplinkos ministerija — Invazinių Lietuvoje rūšių sąrašas
• Kauno Tado Ivanausko zoologijos muziejus — Invazinės žuvų rūšys Lietuvoje
• Lietuvos Respublikos aplinkos ministerija — Keičiasi laukinių gyvūnų, augalų ir grybų rūšių introdukcijos, reintrodukcijos ir perkėlimo reikalavimai
• 58 Pa. Code § 71a.10 — Triploid grass carp (Legal Information Institute, Cornell Law School)
• eCFR — 50 CFR 16.13, importation of live or dead fish, mollusks, and crustaceans (current text)
• Agrožinios — Sodybos vandens telkinio įžuvinimas