[Grass carp articles]
Common name: Grass carp
Latin name: Ctenopharygodon idella
Record weight: In recent years no other record has been in as much danger as the grass carp. With several huge fish dotted around the country, the record has been broken on several occasions in recent seasons. The latest angler to lift the crown is Mr C. Nash who caught one of the handful of giant fish in RMC Angling's Horton lake in June of 2001.
Distribution: Although they have been kept as ornamental fish for many decades, it is only in more recent times that grass cap have become more established. As their name suggests, they do eat plants and so the first large scale introductions in the British Isles were carried out by Liverpool University as an experiment in weed control. The large number of fish introduced to netted-off sections of the Lancaster canal did reduced the amount of weed present and as a result fish have been introduced to many other fisheries. For the most part, grass carp are found in only small numbers as a distraction to other species. They can now be found from Cornwall to Scotland and all points in-between.
Features: The grass carp looks nothing like other species of carp. In fact, grass carp are often mistaken for record sized chub! Like chub, they share a long thin body, with dark tail and bronze scales. Unlike chub, the mouth of the grass carp is smaller and lacks the thick lips of the chub. The eye is also much lower on the head, almost in line with the mouth in the grass carp.
Diet: Despite their name, grass carp do not just eat grass! In fact, apart from young fish, plant material tends to make up quite a small percentage of the fish's diet. As with all coarse fish, grass carp begin feeding upon invertebrates before moving on to a wider diet including soft plants. Larger grass carp would struggle to gain enough nutrition from eating just plant material and so larger invertebrates, particularly molluscs become of increasing importance in the diet.
Spawning: Although quite widespread I know of no fishery where grass carp spawn in the British Isles. This is probably because of the nature of their spawning behaviour. In their native Amur river large numbers of huge grass carp weighing fifty, sixty and even more pounds assemble in the main channel prior to spawning. When conditions are just right, both sexes release their gametes into the water where the semi-buoyant eggs are fertilised. Rather than sink to the bottom, the tiny eggs are carried by the current and develop in the water. Some will be lucky and find their way into warm backwaters where the hatchlings will find plenty of food. A huge proportion of the young fish and eggs will never make it to safety and will either be eaten or washed out to sea.
Growth: In the cold waters and short summers of the British Isles, grass carp are quite slow growing and so we have probably not seen the maximum size for these fish yet. In the warmer conditions of central Europe they grow incredibly fast and can make fifty pounds and over a metre in length in ten years. In the small commercial fisheries common in the UK one pound per year is the average growth rate with perhaps three pounds being found in exceptional circumstances.