Care
The Grass Carp is a large, herbivorous freshwater fish native to China and Russia, which has been introduced to many other countries (including the UK) for biological weed control purposes in rivers, lakes, and reservoirs. The body is an elongated, but chubby, torpedo shape that is dark olive dorsally, fading to a silvery brown on the flanks with a white belly and large outlined scales. In ideal conditions, Grass Carp can grow alarmingly quickly, consuming up to three times their own body weight of freshwater vegetation daily, and as such, require an extremely voluminous home from the outset. Adults can live for around 20 years and have been known to attain 1.5m (60") in length and a whopping 45kg in weight in the wild, so these are not suitable fish for small ponds. Given their appetite for aquatic plants and potential size, these fish are best reserved for large koi ponds or features where planting is not a priority. When other options are limited, they'll happily eat blanketweed and duckweed. Grass carp can be quite nervous and readily jump to avoid dangers, either real or imagined. This is less of a problem when housed in large ponds.
As well as the dark wild form, an albino strain is available which combines high visibility with more modest adult size.
Feeding
Fry and young fish will feed on copepod nauplii, phytoplankton, protozoans, and tiny terrestrial insects/insect larvae, quickly moving on to copious amounts of aquatic vegetation as they grow. Juveniles and adults should be provided with an ongoing source of aquatic vegetation and offered supplementary greenfoods (green based flake/pellets, fresh lettuce etc) where appropriate. In the wild, Grass Carp consume an extensive range of plants including - but not limited to - species from the following genera: Acorus, Azolla, Butomus, Calamagrostis, Calla, Carex, Ceratophyllum, Chara, Egeria, Eichhornia, Elodea, Equisetum, Fontinalis, Hydrilla, Hydrocharis, Juncus, Lemna, Lysimachia, Myriophyllum, Najas, Nasturtium, Nitella, Nuphar, Nymphaea, Phragmites, Pistia, Polygonum, Potamogeton, Ranunculus, Sagittaria, Scirpus, Spirodela, Stratiotes, Trapa, Typha, Utricularia, Vallisneria, and Zizania, in addition to filamentous algae (Chladophora spp.).
Breeding
In the wild, Grass Carp spawn during the summer in the faster flowing, highly oxygenated reaches of rivers, with eggs scattered into the water column. The eggs, which may number several hundred thousand, and are yellow/orange in colour, hatch in 2-3 days and develop whilst drifting downstream in the turbulent currents. This species is bred on a large-scale, commercial basis around the world for biological control of invasive vegetation and for sport fishing, as well as being an important food fish in some countries.
