When we're interested in acquiring a particular type of fish to add to our aquarium or pond, a vast array of breeds opens up before us, with truly diverse sizes, colors, and shapes. However, within this rich diversity, there is one fish that stands out above the rest due to characteristics that have made it very popular in aquariums, sport fishing, and aquaculture. We're talking about carp, One cold water fish most common and versatile in the world.
Carp fish characteristics
La common carp (Cyprinus carpioIt originated in Europe and Asia. It is a freshwater fish. extraordinarily resistant y very adaptable Its habitat is adapted to its environment, allowing it to thrive in rivers, lakes, reservoirs, and slow-moving or stagnant ponds. This remarkable adaptability has enabled its introduction to virtually every continent, and it is considered one of the most endemic species. de peces of the most widespread freshwater on the planet.
Precisely because of this ease in colonizing new environments and modifying the ecosystem, the common carp has earned the "privilege" of entering the list of the 100 Most Harmful Invasive Alien Species in the World According to the International Union for Conservation of Nature, its presence in the wild is regulated or restricted in many countries, as it can displace native species and alter submerged vegetation.
Morphologically, the carp has a elongated and robust bodyIt is relatively tall, with a more or less cylindrical, hydrodynamic silhouette in wild specimens and a taller and more voluminous one in domestic varieties. It has approximately thick, fleshy lips and a protractile mouthThat is, capable of projecting itself forward to suck up food from the bottom, where it usually searches among the sediment.
At the corner of the mouth we find four sensory barbelsTwo barbels, one on each side, act as small tactile and gustatory organs. These barbels help it locate food even in murky water, a common occurrence in the habitats that carp stir up while feeding. Although it has no teeth, it does have... pharyngeal teeth located in the pharynx, with which it grinds food such as hard seeds, small mollusks or crustaceans, pressing them against horny plates of the skull.
The dorsal fin is very distinctive: long, with a strong, serrated first radiusfollowed by 17 to 22 soft rays. The anal fin usually has 5-7 rays, with the first ray also robust and somewhat serrated. Along the flank runs the clearly visible side line, normally composed of about 32-40 large scales in wild carp.
As for its external appearance, the wild carp is completely covered in large, regular scalesThe typical color in nature is brown to greenish on the back, transitioning to tones golden or yellowish on the flanks and belly. The fins are usually bluish-gray and sometimes have slightly reddish edges. In domestic varieties, the color and scale pattern can vary greatly, especially in ornamental lines such as koi carp.
Usually, the adult specimens reach a length that varies between the 60 and 90 centimeters, and a weight that is around 9 kilogramsHowever, under optimal feeding and space conditions, specimens have been recorded that can reach a size of 1,2 meters and weigh up to 40 kgIn natural environments with less food or greater competition, wild specimens tend to be somewhat smaller and flatter than domestic ones.
You know how long does a fish live Carp? It is estimated that some specimens, if they enjoy certain conditions during their lives, can over 60 years of ageAnd in exceptional records, carp are mentioned that have lived even longer. It is, therefore, one of the aquarium and pond fish with greater potential longevitySomething that must be taken into account before purchasing them.
From a physiological point of view, the carp is a fish ectothermic and eurythermalThis means their body temperature depends on the environment and they tolerate a wide range of temperatures. They can survive in stagnant or slightly brackish water as long as the temperature remains within a comfortable range, generally between 17 and 24 ° Calthough they can withstand peaks both below and above that range. They are very resistant to low oxygen concentration already some pollution, which explains its success in degraded environments.
In terms of its behavior, the carp is a fish sedentary and gregariousIt usually travels in small groups of around five individuals, although in reservoirs or large rivers it can form larger schools. During daylight hours it tends to stay near the bottom or in mid-water, searching for food, and is most active at dawn and dusk.
They are mainly omnivorouswith a diet that combines aquatic plants (leaves, roots, tender shoots), insects and larvae, little ones crustaceansworms, zooplankton and even dead fish if the opportunity arises. In nature, this feeding method involves actively stirring up sediment, which increases water turbidity, releases nutrients trapped at the bottom, and can promote eutrophication in still waters.
The breeding season generally begins in spring and extends until the beginning of summer, when the water temperature is above about 18°C. They prefer to spawn there. shallow waters dense with vegetationwhere the females lay their eggs, which then adhere to plants and other substrates. The common carp is oviparous and reaches sexual maturity around [age missing]. Age 4 Under normal conditions, although many studies indicate that the Males usually mature slightly earlier than the females.
Females can lay up to 300.000 eggs on average per season, although large specimens have been known to lay over a million eggs. Depending on the water temperature, the eggs can hatch in as little as 3-4 days Hatching occurs when the water is warm (around 28-30°C) or takes a little longer if the temperature is lower. The fry are born at only 6 mm in length and consume their yolk sac in a few days, after which they begin to actively feed on plankton and small invertebrates.
In addition to its natural reproduction, carp have been intensively farmed in ponds and aquaculture systems for centuries. It is one of the most important species. de peces earlier domesticated by humans Currently, dozens of lineages and strains are known, selected for characteristics such as rapid growth, scale arrangement, or color.
Although the common wild carp does not appear to have very bright colors, in China and, more specifically, in Japan, captive breeding led to the development of a new variety of bright and vibrant colors, smaller in size and intended for ornamental use, known as koi.
Kois fish
El koi It is a domestic ornamental variety of the common carp, developed from different lineages of Cyprinus carpio Selected over generations. Unlike other related species whose success has come from the hunting and fishing sectors, the koi has been popularized as a pet, protagonist of ponds and water gardens around the world.
As a curiosity, koi In Japanese, it means "carp," but it's also a homonym for "love" or "affection." The breeding of ornamental carp has been documented for centuries in East Asia, but it reached enormous popularity in Japan when rice farmers began selecting carp with brighter colors and defined patterns to beautify their ponds. Over time, varieties with combinations of white, orange, red, black, yellow, or blue were established, resulting in more than a hundred recognized patterns.
The famous Japanese koi ponds They became symbols of beauty, harmony, and good fortune. From there, the koi spread to other countries outside of Asia, and the figure of the professional carp breederspecializing in specific lines and high-value specimens. Some show koi carp can reach very high prices, a reflection of the genetic selection work, the rarity of the color pattern and the prestige of the breeder.
Although koi share many characteristics with the common carp (resilience, adaptability, omnivorous diet, gregarious behavior), they usually exhibit a slightly taller bodya whirlpool bath, smaller head and greater variability in colors and scale types. They retain the same hardness and tolerance to varied water conditions, which explains their success in outdoor ponds.
How to take care of our Kois or Carp?
As mentioned earlier, koi have become the domestic fish par excellence in garden ponds and large aquariums. They are highly recommended for those starting out in the hobby and wanting to try a species that requires relatively simple carebut that at the same time be striking in appearance and color and offer a long coexistence.
The koi fish has a predilection for the middle or lower parts of the aquarium or pond, rising to the surface to feed or breathe when oxygen is scarce. They can live in small groups Up to 6-7 individuals No problem, as long as the water volume is adequate. However, it's worth remembering that they are fish of large potential size and long lifeTherefore, the project needs to be properly planned from the beginning.
When living with other species, carp and koi generally exhibit a docile characteralthough they may sometimes exhibit certain aggressivenessespecially with smaller species or in aquariums small and densely populatedIn these cases, it is easy to observe how these fish harass other inhabitants, compete for food, and may even nip at more delicate fish.
Therefore, it is not advisable to house them in small fish tankslike the typical round ones, nor in overcrowded community aquariums. This not only reduces aggression problems, but also promotes a healthy growth and reduces stress. Space is vital for these fish, and therefore aquariums are recommended. equal to or greater than 90 liters of water for young specimens, and much larger volumes (ponds with several thousand liters) for groups of adults.
La water temperature This doesn't usually pose a big problem, since, as we've already mentioned, these animals adapt very well to climatic conditions. However, if given the choice, these small carp They tolerate moderate cold better. that excessive heat. Very high temperatures can lead to oxygen deficits in the water and thermal stress, which can be lethal.
In outdoor ponds, there have been cases where carp and koi have even survived frosts with the water surface partially frozenProvided the pond is deep enough to create layers of liquid water where animals can take refuge. However, the intense summer heat can be more dangerous, so it's advisable to offer shaded areas and ensure a good oxygenation through waterfalls, aerators or filter outlets that agitate the surface.
With regards to eatingAs already mentioned, they are omnivorous (although with a slight tendency towards carnivory), so their basic diet is not complicated. Flake or pellet feeds specifically for carp and koi that we find in any establishment specializing in animals, is sufficient to cover their daily needs.
If we want them to enjoy a richer and more varied diet, we can provide them with live or frozen food such as small insect larvae, bloodworms, daphnia, or small crustaceans used in fishing. In addition, some plant-based supplements are always welcome: leaves of blanched spinach, skinless peas, very thin slices of zucchini or cucumber, or even the occasional consumption of natural vegetables from the pond, where we will see them taking small bites of the soft plants.
It's important to know that in winter, koi and carp enter a process of lethargy When the water temperature drops below certain levels, their activity decreases considerably, their metabolism slows down, and consequently, appetite decreases greatlyIf we notice that they don't eat the food or only eat minimal amounts when offered, it's not advisable to insist. cold water supercharging This can result in rotting food, spikes in ammonia and nitrites, and serious health problems in the pond.
Another very important issue is the water filtrationIn the case of carp and koi, this is even more critical than in other species, since it is de peces large that They produce a lot of waste. and stir up the bottom while searching for food. This filtering should preferably be done in a external, with powerful filters that combine mechanical filtration (to retain suspended particles), biological filtration (nitrifying bacteria that transform ammonia into less toxic nitrates) and, if possible, some chemical filtration (activated carbon, specific resins).
If our fish are in a small aquarium without a filter, we must do frequent water changesThis species generates a large amount of waste that quickly depletes dissolved oxygen levels and can accumulate toxic compounds. We recommend using an external filter. like these, always sized above the actual volume of water to ensure good quality.
In ponds, in addition to the filter, it is advisable to monitor the water hardness and pHMost carp and koi thrive in medium-to-high hardness water with a slightly alkaline pH, between 6,5 and 9Maintaining stable parameters, along with good oxygenation and the absence of ammonia or nitrite spikes, will be the foundation for carp to look healthy, active, and with intense colors.
Varieties and species of Carp fish
The market offers us a wide variety of carp shapes and lineages for our aquarium or pond. Despite belonging to the same base species (Cyprinus carpio in most cases), there are many species and varieties of tents in which the colors, body size and scale arrangement They can be very different.
From the point of view of scale arrangement in the common carp, several are usually distinguished main forms:
- Common or full scale carp: body completely covered with large, regular scales. It is the form closest to the wild carp, with an elongated and very hydrodynamic body. Within it, the following are often distinguished: wild common carp (more fibrous, slower growing, and cylindrical in body, rarely exceeding 20 kg) and the common domestic carp (more voluminous body, tendency to grow in width and height, very marked belly and hump, with potential to exceed 30 kg under intensive breeding conditions).
- Mirror carpIt has large plates of irregular scales distributed across its body, leaving areas of exposed skin "bare". These large, loose scales are the result of human selection.
- Linear tent (linear or linear mirror): A variety of mirror carp in which the scales are arranged in one or two more or less continuous lines along the flanks, following the lateral line. The rest of the body may be almost scaleless.
- Leather carp: practically devoid of scaleswith smooth, dark skin. Sometimes it retains a few isolated scales near the base of the dorsal fin or the tail.
- Full scaled: a term commonly used in the field of carpfishing to refer to specimens with particularly attractive scale arrangement, often a combination of mirror carp and full scale, with very defined and striking patterns.
As for the ornamental varieties Besides koi, which we usually see in cold-water aquariums, several related lines of goldfish stand out (many of them derived from Carassius auratus, the classic red fish or goldfish), which are often popularly grouped together as “carp” because of their appearance:
- American comet: is the most widespread variety because it is the one that less care requiredTheir fins are not as long, and their bodies are slimmer and more streamlined. They are very active and hardy fish.
- Ryukin or Veil TailIt has very long fins and a chubby bodywith a pronounced hump behind its head. Its movements are slower and more elegant.
- at the rate y Lion's Head: very similar to the ryukin in general form, but with some cephalic papillae very distinctive, a kind of fleshy "hood" over the head that gives them an unmistakable appearance.
These three varieties (comet, ryukin/veiltail, and oranda/lionhead) are the most common in cold-water aquariums, but many other beautiful varieties exist, such as telescope, ranchu, and sky pearl. It's worth noting that, although they are popularly called "carp," many of these forms belong to the genus *Polyspora*. carassius and not to the one of Cyprinus, although their General care is similar to those of koi carp in terms of temperature, space and water quality.
In the field of sport fishing and carp fishing, different types of carp are also discussed according to their origin and morphology: common carp, royal carp (tall and very robust body), mirror carp, leather carp, linear carp and full scaled varieties, In addition to koi carp that occasionally appear in reservoirs or rivers after irresponsible releases. Each one has its own aesthetic characteristics, but in terms of biology and behavior They share most traits.
The enormous diversity of shapes, colors, and patterns of scales that we find today is the result of centuries of domestication and artificial selection by humans. From the wild carp that inhabit rivers and lakes of Europe and Asia to the high-lineage koi and the ornamental aquarium varieties, they all share the basis of an extremely adaptable, long-lived and resistant fish, which has managed to occupy a prominent place both in natural ecosystems and in culture, gastronomy, sport fishing and aquariums.
Know in detail the characteristics, varieties and care Understanding carp allows us to enjoy this fish responsibly, minimizing its impact on the natural environment, providing it with the best conditions in ponds and aquariums, and appreciating, at the same time, the impressive history of domestication and diversity behind one of the most important and emblematic fish in the world.