Introduction to Discus Fish
The discus fish of the family Cichlidae is native to the Amazonian river basin flowing through South America. There are three species of discus fish under the genus Symphysodon, a name by which the fish is also known. Discus fishes are widely used as aquarium fishes, given their distinctive shape and body patterns, bright colours and behaviour. Aquaculture of discus fishes is also a major industry, especially in Asia.
In this article, we will focus on the habitat, behaviour, distribution, morphology, etc., of discus fishes in addition to learning about discus fish care, discus fish breeding and discus food.
[Image will be Uploaded Soon]
Morphology of Discus Fish
The body of the discus fish is round and laterally compressed in shape. Their round shape is attributed to the fact that there is a lack of extra or extended finnage. In fact, they have been given the common name, ‘discus’ owing to the shape of their body. One can observe patterns of shades on their sides in colours of blue, brown, red and green. Owing to selective breeding by aquarists on discus, certain variants (not found in the wild) are more brightly marked.
The typical length reached by the species of discus fish usually varies between 12.3 to 15.2 cm, i.e., 4.8 to 6.0 inches. However, the species of discus fish bred in captivity have been known to reach lengths of up to 23 cm or 9 inches. A discus fish adult usually weighs around 150 to 250 g. Sexual dimorphism has not been particularly observed in discus fishes but males may occasionally reach larger sizes as compared to females. In the solid red discus breeding variety, also known as the red cover or the red melon, however, females have been occasionally reported to be redder than males.
Discus Fish Habitat and Distribution
Discus fish or the Symphysodon species form part of the Neotropical fish fauna that is highly diverse in nature. The discus fish are distributed in the lowland basin of the Amazon where they inhibit the margins of rivers and floodplain lakes. Although the species is typically restricted to habitats of blackwater, they are likely to experience brief whitewater floods. Of the three species of discus fishes, Symphysodon aequifasciatus (Blue discus) is generally seen in clearwater whereas Symphysodon tarzoo is found in white as well as black water. Symphysodon discus, on the other hand, is restricted to blackwater habitats only.
The species of the fish typically prefer to dwell in lentic habitats such as flooded forests and floodplains. As such, in contrast to primary sections of whitewater rivers, the discus fish inhabited whitewater barely comprises suspended material.
The geographic distribution of the three species of discus fishes is also diverse. Symphysodon discus is limited in its distribution to the upper Uatumã, Nhamundá, Trombetas. Rio Negro (lower reaches), and Abacaxis Rivers. The species of Symphysodon tarzoo is seen to occur in the West Amazon, mainly upriver from the arch of Purus whereas downriver from this arch in the East Amazon is where the species of Symphysodon aequifasciatus is typically found.
Outside this native range, in the far western Amazonas’ Nanay River, an aquarium exporter introduced discus fishes 30 years or earlier, from stock that had origins in the Tefé area. In addition to this, discus fish are also farmed extensively in a number of fish farms across Southeast Asia. From here, discus fishes are supplied to home aquaria all over the world.
Discus Fish Behaviour
The species of discus fishes display highly social behaviour. They typically occur in groups that are often likely to comprise several dozens of individuals. This behaviour displayed by the discus fish is unique among the fishes of the Americas belonging to the order Cichlidae. At the time of breeding, the mating pair is seen moving away from the school. This behaviour is thought to be a means of reducing the risk of cannibalism of the younger fishes.
Typical of the order Cichlidae, brood care in discus fishes is also highly developed. Both the parents care for the young in discus fishes. In addition to this, the larvae in discus fishes live up for their first 4 weeks on the secretion produced by the skin of adult discus fishes. Parents stay in proximity to their young ones during the first two weeks which allows the latter to feed easily. The parents of the discus fishes feed their progeny with the mucus of their skin during these two weeks. In the last two weeks, the parents swim away, resulting in the gradual weaning off of the young ones allowing them to start fending for themselves. Discus fish attain their sexual maturity usually within a year.
Studies have shown that the unique parental care displayed by discus fishes, where the young feed upon the skin mucus of their parents allows transferring of key microorganisms from the parents to the fry. This transmission of microorganisms from parent-to-offspring behaviour is thought to explain the high survival rate observed in the case of discus fry that is raised with their parents as opposed to the low survival rate of the discus progeny raised by fish breeders artificially. Fish breeders generally make use of brine shrimp, egg yolk or other types of replacement foods to raise the discus fry artificially.
Discus Fish Food - Diet of Discus Fish
The species of Symphysodon are primarily known to feed on algae and other plant material along with detritus (periphyton). Occasionally, consumption of small invertebrates by discus fish is also observed. During the season of high water, invertebrates can comprise as much as 38 percent of the stomach content in wild species of S. aequifasciatus. This, however, decreases during the season of low water and generally remains lower year-round in the other species of discus fish. The intestines in the case of discus fishes are relatively long as in the case of herbivores or omnivores which is different from the more predatory cichlids.
Discus Fish Breeding
Discus fish, also at times known as pompadour fish, has a cult following when it comes to collectors. This has allowed for the creation of a multimillion-dollar industry internationally with the participation of reputed breeders. Breeding of discus fish requires breeders to buy several specimens of the young one as the discus fish species are known to choose their own mates. Discus fishes are only capable of tolerating small changes to their environment. Breeders are required to maintain optimal water conditions including acidity, water hardness, the temperature in order to successfully breed discus fish. The discus tank needs to be a planted discus tank for breeding purposes. Amazon sword plants and their different varieties along with large water plants such as Echinodorus are among the ones favoured by discus fish species. The addition of leached root stumps also provides the necessary cover and places for lodging of the discus fish pair while breeding.
During discus feed breeding, spawning generally occurs on a flat vertical surface. Many pairs of discus fish, however, prefer to lay eggs on a plant with broad leaves such as the Amazon sword. Eggs before hatching are fanned for three days. The fry then is moved around the aquarium several times through the parents’ mouth for 4 more days. By the seventh day, the fry starts to swim freely while still feeding off of the side of their parents.
Breeders must not take the discus fish parents out of the permanent breeding tank as the parents do not feed on the fry or young fish. The young fish can then be moved into a separate tank for allowing them to grow fully.
Discus Fish in Aquarium
Discus fish are valued for their characteristic, striking appearance and are thus, kept in the home aquarium by fishkeepers. Given their need to be kept in groups and their strict requirements for water quality, discus fish are often considered difficult to keep. Breeders are often known to choose individuals that are more adaptable to tap water conditions.
The average lifespan of discus fish in home aquariums is 10 years ut they are known to be able to live up to 15 years and reaching about 8 inches in length. Akin to other fishes in the home aquarium the discus fish food can be anything that fits within their mouth.
Discus Fish Care
The aquarium size for discus fishes is a minimum of 55–75 gallon due to their size.
Discus fish are known to prefer warmer waters. The ideal water temperature to keep discus fish, in general, is 840F to 860F while for raising or growing juveniles it is about 860F to 880F. In order for breeding or keeping in a planted tank, the ideal temperature is 820F as this temperature mimics the natural environment of the rainy season in the Amazon.
Discus fishes prefer acidic and soft water with a pH of 7 or below and a general hardness or gH of 1 to 3.
Discus fish food in the aquarium ideally should include pellets, flakes, and frozen or live foods. It should be taken care that discus fish are not fed more than 3 percent of their body weight. An adult discus fish should be ideally fed about 2 to 3 times a day.
Any non-aggressive community of fish big enough not to be seen as snacks can be kept along with discus fish in an aquarium. Care should be taken to ensure that the other fauna is capable of withstanding the warm water requirements of discus fish.
[Image will be Uploaded Soon]
Fun Fact About Discus Fishes
The discus fish is popularly known as the ‘King of the Aquarium’
The World Discus Competition takes place every year in Guangzhou, China.
The North American Discus Association is aimed towards supporting hobbyists as well as in supporting wild discus.
FAQs on Discus Fish
1. Is it Difficult to Keep Discus Fish?
Ans: Discus fish require adhering to strict quality when it comes to water requirements and as such, they are difficult to keep in aquariums. However, aquarium hobbyists make continual efforts to breed and raise discus fish because of their striking wavy markings of green and blue in colour.
2. Why are Discus Fishes So Expensive?
Ans: The reason that the discus fishes are so expensive is related to different conditions. These include:
Requirement of Warmer Water Temperatures as Compared to Other Tropical Fishes
Discus fish requires warmer waters to thrive and this is a big cost especially for breeders in colder climates. This is the reason for the high prices of the retail discus fishes because the losses have to be accounted for by the seller. Therefore, it is cheaper to import discuss from Asia where the cost of growing them in breeding facilities is lesser.
Quality of Food and Water
Discus food is expensive irrespective of whether the food is off the shelf or homemade. Additionally, the requirement of water in the case of discus fishes is very narrow-range and the breeders have to work hard to ensure that these requirements are met. These strict regulations also contribute towards discus fish being expensive.
Growing Time
A lot of time is required in the growing of discus from the fry stage into an adult. Given the discus fishes usually go through a culling process, the adults of higher quality are also fewer. The expense of discus fish is directly proportional to the time and effort put down by breeders in order to raise high-quality adult discus fish.
Demand for Discus Fishes
The supply-demand scenario is also the reason behind the high prices of discus fishes. There are a lesser number of breeders, especially in the US and thus the production of the discus fishes are nowhere usually near the demand that there is for particular strains of the fish. Import of discus fishes is also the reason behind their high price as there are a lot of expenses and risks that need to be covered. From the trans-shipper housing them to absorbing any kind of losses due to carrier negligence along with providing the buyer with some kind of guarantee, the costs add up making the discus fish even more expensive.
Their lower supply combined with the high demand owing to their striking appearance can also load to surcharging by the sellers, thus increasing the price.
Breeding Conditions
Breeders have to ensure that optimal conditions of breeding are met to raise high-quality adult discus fishes. This includes raising the fishes in warmer water with lesser fauna along with ensuring that the water is soft and slightly acidic. This is a labour-intensive process. All of these costs add up to discuss fishes becoming more expensive for the buyers.
3. Is it Necessary to Keep Discus Fish Together?
Ans: Discus fish are sociable by nature and do better in groups. It is thus, important that a school of discus fish ate kept together for them to be able to choose their own mate for breeding. This is also particularly important when it comes to breeding discus fish.
4. How Frequently Should Water Be Changed in Discus Fish Aquariums?
Ans: Similar to the majority of tropical fishes, discus fish aquariums also require frequent water changes in order to maintain the school. It is recommended that the water in the discus fish aquariums is changed at least once a week. Some breeders also opt to change about 20 to 25 percent of the water in the aquarium 2 to 3 times a week.
