Fish Facts: Crucian Carp

I caught my first ever Crucian Carp as a teenager from a local fishery from where I lived. 

The fishery was a series of very small ponds that were dug into a ditch system near a farm and were incredibly shallow. It was never a particularly good fishery, and remains so today unfortunately. During the summer months, when the weather heated up, the fishery dried down to the bottom and the silt cracked in the sun. Though work has been done to it in fairly recent years, it still gets extremely low and often dries up still. 
Anglers who fish it and have stuck with it all these years claim to have caught big double figure Carp from it, but when the water is low, and only about a foot deep or lower, it’s hard to believe the claims.
But I digress, back when I was a teen fishing it, you couldn’t imagine many fish surviving in the low to dry conditions of the ponds, especially when you could walk around and see the bottom and see no signs of any fish. But sure enough, when the water levels rose after rains, Aaron and I could always come down here and inexplicably have a successful day of Crucian Carp fishing with maggots on a basic float fishing setup. It seemed to us impossible for any fish to survive in these conditions, but somehow the hardy Crucian Carp always did. I don't know if they still reside there, as eventually we discovered better fisheries as we grew up, and I've never returned there.
For many years we always assumed that Crucian Carp were a species of fish that were small, perhaps only as big as your hand, as these were the biggest of them we ever caught from the venue as kids. This was until the hot summer of 2006 when we finally went to fish at the now famous Crucian Carp day ticket mecca of Marsh Farm in Milford in Surrey.
On a roasting hot day we fished Harris Lake and I hooked several Crucian Carp. I shall always remember the moment when the first one boiled on the surface just before netting. I naturally, from my experience, believed it to be a Tench I had hooked, as it would have been too big to be a Crucian, but it was indeed a Crucian Carp that I landed.
I remember Aaron and me crowding around it on the unhooking mat and feeling the sense of shock, disbelief, joy and excitement in the air as we openly marvelled at the size of it! It was 2lb 9oz in weight, actually a very average sized one for this fishery, but to us, being the first one this big we had ever seen, it was an absolute monster! A mythical creature that we could have never dreamed of.
Since then I caught many Crucians up to and around the same size from various fisheries, and I have come to love them so much as a fish that I rate them number 5 in my list of favourite freshwater fish in the UK.

The Joy of the Crucian Carp

The Golden, Shy Biting Survivor

Crucian Carp
(Carassius carassius)

The Crucian Carp is a member of the Carp family Cyprinidae.
At first glance it looks very similar to the Common Carp members of the same family, but it is a species that grows much smaller, being only a medium sized fish.
The Crucian Carp is much rounder in body then the Common Carp, its dorsal fin is higher and it has a flatter body, but more noticeably it lacks barbules either side of the mouth.
Their snout is quite stubby, and they have a terminal mouth.
They are often confused with Goldfish, and various interbred Carp, but there are many different ways to tell in more detail if it is a true Crucian Carp, the most popular test being to count the scales along the lateral line of the fish, which should number between 27-30 scales if it is a true specimen.
The body of a Crucian Carp is generally golden bronze in colour, some people describing it as buttery gold, becoming paler down towards the belly. The color of the Crucian darkens as the fish grows older. Its fins are convexly rounded and are a reddish, orange colour
The Crucian Carp is believed to be the only indigenous Carp species to the UK, unlike the others who at some point were imported into the country.
They are a schooling fish, moving about in large groups to feed and better survive predation. These schools are typically made up of similar sized and aged fish, usually the same year class. They can live for up to 10-12 years.
They are a shy species of fish, that are easily spooked and particularly famous with anglers for being very shy biters.
The British record Crucian Carp (as of 2020) stands at 4lb 11oz and was caught in August 2020 from Milton Abbas Fishery in Dorset by Craig Smithson.
A Crucian Carp of 2lb+ is considered a specimen fish

A Typical Crucian

Habitat

Crucian Carp thrive best in still or slow flowing waters such as lakes, ponds, reservoirs and slow flowing streams and rivers.
They prefer waters where there is plenty of aquatic submerged vegetation to both hide, breed and feed in, and are usually found swimming near the bottom of these waters, certainty in the bottom water column over all others
They are believed native to England, and can be found in Northern European regions from as far north as the Arctic Circle in Scandinavian countries to as far south as France and the Black Sea. They can also be found in Russia, where they can even be found in slightly brackish rivers.

Diet

Crucian Carp are an omnivorous species of fish, and eat a wide variety of natural food. Insect larvae, crustaceans, and zooplankton are on their menu, as well as filamentous algae, water plants and seeds.

Monsters in the Depths

Breeding

Sexual maturity of the Crucian Carp varies depending on the weather conditions of that area. In colder climates they reach maturity at a much older age than those fish living in warmer climates. In the UK the Crucian Carp tends to reach sexual maturity when they are 2-5 years old at around 3 ½ inches in length. Male Crucians mature much earlier than females.
They are a batch spawning species and the females lay around 100,000 yellow/orange eggs about 1 ½ mm in size, which they stick to underwater vegetation.
Crucian Carp breed when conditions are right, usually in May/June when water temperatures in their habitat exceed 18 degrees. Breeding is usually brought on after a rainfall.
Crucian eggs hatch quickly after as little time as 4 days and the fry live among the vegetation feeding on plankton and crustaceans until they grow big enough to venture out into the open. 
Crucian Carp hybridise with other carp species easily, such as the common domestic Goldfish.
They also breed with Common Carp creating what breeders of these fish call an F1. F2 Carp are the resultant crossbreeding of two F1 Carp. These crossbreeds are favoured by match anglers as they retain the fight of a Common Carp, but remain small like the Crucian.

Predators

Crucian Carp are preys upon by aquatic predators such as Pike and Perch, and where present, Catfish and Zander.
Above the water, a heron, egret or cormorant will make a meal of a Crucian Carp, whereas smaller birds like grebes and kingfishers will eat the fry.
Mammals such as mink and otters find Crucians easy to catch as they prefer shallower waters.

Breeding the new Generation

Survival

Crucian Carp are very wary, shy fish, and need to be this way to help avoid their predators. They travel around in schools so that there is safety in numbers. But this is not the extent of their quite unbelievable survival skills. 
Crucian Carp are renowned for being extremely hardy fish. But few realise quite how hardy they can be! 
They show remarkable adaptations to their environment and can cope with some truly extreme conditions for such a lowly looking fish.
They can survive perfectly in the smallest, weediest pools that hold water of poor quality, and even in water that has dangerously low oxygen levels, even surviving completely out of water for several hours.
During anoxic conditions (times with little or no oxygen) they survive by anaerobic respiration, being able to break down energy from their bodies without the use of oxygen. 
In summer months when the water drops dangerously low they survive by burying themselves in the mud or silt at the bottom pond or lake bed. Using this amazing adaptation they can survive these anoxic conditions and amazingly remain this way and survive for several weeks until rainfall refreshes their home.
The same is also true in winter months, when ice can block out the oxygen diffusion in the water. They can also slow down their metabolism in these cold conditions to expend less energy and survive like this for months until the weather warms. In the most extreme conditions Crucians can even produce ethanol in their muscle tissue and livers to survive freezing solid in temperatures that reach as low as 0 degrees.
Truly remarkable!

Conservation

Despite being an incredibly hardy fish, Crucian Carp are becoming severely threatened as a species. This is not caused by predation or pollution, but by the mere act of them breeding.
As mentioned, Crucian Carp cross breed with other Carp very easily. Introducing Common Carp, and particularly domestic Goldfish into a habitat containing true Crucian Carp is devastating. The resulting offspring over several generations can reduce a habitat of crucian carp into a habitat of contaminated hybrid crosses in no time.
The National Crucian Conservation Project, working along with The Angling Trust and the Environment Agency continuously work to stop this cross breeding from happening by monitoring fisheries that contain true Crucian Carp and encouraging new fisheries to stock pure unhybridized stock from reputable breeders.

Float Fishing is Best

Fishing

The most common and best way to catch Crucians is to float fish for them with a light tackle, either using a light, bendy match rod or a pole. Using this technique, the line should be low diameter, maximum 3b line and preferably lighter, and hooks should be small, size 20, 18 or 16 depending on what bait you are using. Plumbing the depth so that the hook is either on or just off the bottom of the swim is essential. Small pole floats, self cocking floats or quills are the best floats to use, that require little to no shot to hold position in the water.
Shotting on the rig should be spaced out and set to show even the smallest and delicate bites, as Crucian Carp are shy biters and a bite on the hook can register as even the tiniest dip or rise of the float.
Top Crucian Carp baits are maggots and casters, chopped worm, sweetcorn and small cubes of luncheon meat.
To locate Crucians, fish in shallow areas of the venue, alongside reed beds, submerged weed beds, by lilies and in the margins and approach and fish alongside the water quietly as they spook easily.

Bar of Buttery Gold

So that explains how those Crucian Carp in the venue I fished as a teen survived the drying up of all the water. It's amazing to me that a fish can adapt so well to these potential life threatening conditions. They just laid there in the mud until the water returned.
There is something truly relaxing about Crucian fishing to me. Perhaps it's because of the habitat they tend to live in and the weather it's best to catch them in. Sitting quietly beside a silent lily covered pond, plopping a float into the still margins on a warm, sunny summers day. It's one of those types of fish where you know that fishing for them in these conditions will lead to a slow, dreamy day of quiet patient angling, where you could easily snooze and doze the day away, fully relaxed, if it wasn't for the concentration needed to see the slightest millimetre of movement on the float that indicates a proper bite.

I have a great love for Crucian Carp and fishing for them in my heart.
The days I've spent Crucian Carp fishing as I've described above is one of the reasons why Crucian Carp are so high at number 5 in my favourite UK freshwater fish list. 
They are beautiful, characterful fish that are a delight to catch. They are not too common to be troublesome or boring, and tricky enough to catch where you really need to hone your skills as an angler. They can be a challenge to catch, making a capture of one, particularly one of a decent size, is a true angling achievement to be proud of.