Discus Fish
wikipedia
Discus Fish are freshwater perciform fish, peculiar cichlids native to
the Amazon River basin. There are two recognized species, both
within the genus Symphysodon: the red discus or common discus
(Symphysodon discus) and the blue discus (Symphysodon
aequifasciatus). The two species are very similar and may
interbreed, producing a number of hybrid strains. Details
regarding the precise number of subspecies have not been
finalized. Discus are most closely related to the genus Heros.
The first special characteristic of the discus is its flattened
body shape. It is compressed from the sides to a dish or discus
shape. Although patternation varies, most are showily colored in
shades of green, red, and blue. The height and length of the
grown fish are both about 20–25 cm (8–10 in).
The second special characteristic of the discus is its care for
the larvae. Like all cichlids, the parents care for the young but
the discus has a unique way of doing so: the parents produce a
secretion through their skin, off which the larvae live during
their first few days. The young can be seen grazing off their
parents.
The discus are shy and peaceful aquarium inhabitants. They are
sensitive to stress and disturbance or lack of protection. The
best cohabitants may be angelfish (although many aquarists claim
that keeping them together with angelfish will introduce
parasites and/or diseases in them) and small characides like
tetras. The Uaru is another preferred tank-mate of the discus.
However, small fish may be intimidated by the big discus fish or
even eaten. Small chacarins like neon tetras are often found in
the gut of wild discus, so they might not be the ideal
cohabitants, but the ideal food.
Also suction mouth ancistras (plecos) prove less than ideal for
discus since they often attach themselves on the sides of discus
and eat their mucus membranes.
The popularity of the discus has given it its nickname among
aquarists: "the King of the aquarium."
Caring for Discus Fish
Generally, discus are considered difficult to care for and breed,
but can be successfully kept by almost anybody with a little
knowledge and effort. Appropriate water conditions:
• 78-88º F (26-31º C). Most people keep their discus at about 85º
F (29º C).
• pH and hardness don't appear to matter (within reason) for
general discus keeping. In order to spawn discus, low hardness
and low to neutral (6-7) pH may be necessary for the eggs to be
fertilized. Most commercially produced discus have been raised
and spawned for generations in water that bears little
resemblance to Amazon blackwater conditions (very low hardness,
very low pH) and may successfully spawn under a broad range of
water conditions.
• Pollution WILL NOT BE TOLERATED. In terms of tank conditions,
this is really the big 'secret' to keeping discus healthy. Before
buying your first discus, be sure your tank has a high capacity
biological filter and has fully cycled (which usually takes a
month or more.) Once a tank is established and stocked with
discus, perform regular large water changes; at least half the
tank, once a week. (Many breeders use much heavier water change
schedules; as much as 3/4ths of the tank's volume every day!)
Picture Discus Fish
Feeding Discus Fish
After keeping the water clean, feeding discus is the other
challenge. They have no unique nutritional requirements; they can
be raised on just about any high-protein fish food. The problem
is that discus are often extremely cautious about adapting to new
foods; it's not unusual for them to go for weeks without food
before accepting a new type of food. Whenever you buy discus,
ALWAYS ASK WHAT THE FISH ARE EATING.
After starving for a month discus will almost always accept a new
food, but if you're buying younger fish, that can also stunt growth.
ALWAYS find out what sort of food the fish are accustomed to so
you can get them eating in their new home right away. If you would
prefer to feed them something else, you can then take your time
to switch them over to the new food by mixing a little of it into
their old food.
Lighting:
Discus appear to be indifferent to lighting; contrary to some
popular opinion, extremely bright lights (for plants) do not seem
to bother them. If your fish are 'jumpy' or hide most of the
time, something else is wrong (they may simply not be accustomed
to their new home yet.)
Buying Discus Fish
The ideal way to buy discus is from a local breeder, where you
can ask questions and see the fish first-hand. For many people,
however, the only options are pet stores and mail-order. Pet
stores are probably the best option if you only want one or two
fish (which may be wise if you've never kept discus before.) If
you're willing to buy a larger group of fish (such as in hopes of
eventually getting a breeding pair), mail-order is the better
bet. (The quality of the discus carried by pet stores can be
quite spotty, and mail-order prices are often actually better.)
The idea of having expensive live fish shipped in by FedEx is
often startling to first-time buyers, but this approach actually
works extremely well; deaths are rare. None-the-less, check your
breeder's policy on shipping deaths. Most breeders will refund
your money if a fish arrives dead. Such overnight package
shipping is expensive; within the US, expect to pay about $75 or
more. Some breeders are willing to ship by slightly slower
methods (such as US Express Mail), which can be less expensive.
If you don't want a large number of fish and know other aquarists
with an interest in discus, consider placing a group order to
save on shipping.
Most discus are sold at about the 2-3" size. At this size, they
will have some (but not all) of their adult coloring and
markings. Some breeders will sell fish at the 1" size, which have
virtually none of the adult coloring yet (but may be less
expensive.) Generally, expect to pay anywhere from $18 to $40 for
the more common color varieties (depending on size, type, and
breeder.)
It can take up to a year for discus to fully develop the
brilliant color and patterns they are famous for, making it
sometimes difficult to judge juveniles.
Upon first arriving, discus are probably best kept in their own
tank, where they can be closely watched and will not have any
competition for food. Once the fish are eating well and seem
comfortable they can be moved to other tanks (or additional
tankmates added.)
Common Discus Color Varieties
There are three layers of color on discus: The base color (which
usually ranges from cream to red-brown), the secondary color (a
metallic color, usually a blue or green color) and the black
pigment that makes up the black vertical bars and allows the fish
to darken and lighten at will.
Most discus strains have either a golden or reddish base color.
The secondary color is often striped down the sides of the fish,
although many strains (such as 'solid cobalt' or 'blue diamonds')
have secondary color that eventually covers most or all of the
fish's body.
Notable Discus color varieties:
Wild forms:
Brown: The most common color form in the wild; these fish have a
brownish base color with minimal stripes of secondary color only
along the head and fins.
Blue/Green: Similar to the Brown, but with more secondary color
(either bluish or greenish.)
Royal Blue: The secondary color forms stripes across the entire
body, with a golden base color. These splendid fish are the basis
of many of the developed color strains, and are primarily
responsible for the early fame of discus. Royal Blues can usually
be readily distinguished from selectively bred color forms by
their less even base color, with the golden color becoming a
brighter yellow around the breast area.
Red Spotted Green: A reddish base color with greenish secondary
color with 'holes' in it (producing spots of the red base color
showing through.) This handsome color form is extremely rare in
the wild, but is produced by several breeders.
Heckel: Possibly a separate species, Heckels are identifiable by
two vertical black bars that are much thicker than the others.
Common Bred forms:
Red Turquoise: A red-brown base color with stripes of blue-green
secondary color, normal black pigmentation (bars).
Solid Cobalt: Golden or light brown base color, but when fully
mature covered with a blue secondary color. Black pigmentation
may be normal or incomplete (some vertical bars missing.)
Blue Diamond: Essentially a 'solid cobalt', but the black bars
have been completely removed through selective breeding. The
reduction in black pigment gives these fish a bright, lighter
blue color than most 'solid' discus.
The Pigeon Blood mutants: These fish have a gene that disrupts
the distribution of the black pigment. As a result, they lack
vertical black bars (but often have 'freckles'). The lack of
black pigment makes their base color much lighter and brighter;
as a result, discus with this mutation may show brilliant red or
yellow (or even pale cream) primary color. Most of these strains
are no longer called 'pigeon bloods' per se, but are easily
identifiable by the bright base color, freckles, and lack of
black vertical bars. All pigeon bloods are the descendant of a
single fish found in Eastern Asia in the 1980s. Since the trait
is dominant and appears to be controlled by a single gene, fish
bearing this mutation can be crossed with any other color strain
to produce novel new 'pigeon blood' types. Pigeon bloods do have
one drawback: They cannot darken at will (as normal discus can).
This can make it difficult for them to raise fry, which are
attracted to their parents by seeking out a dark object. (Normal
discus darken when spawning or stressed.) The fish shown at the
top of this document is a pigeon blood. (High quality pigeon
blood types have few or no 'freckles'.)
Snake-skins: These fish have a mutation that makes their
patterning 'tighter'; as a result, they have about twice as many
black vertical bars, but also have tighter, finer secondary color
patterns than normal discus.
There are no real rules or authorities on what constitutes a
unique color variety or what to call it. A particular form may or
may not breed 'true' (with offspring very closely resembling the
patterns of their parents.) Generally all of the common,
established forms breed true. The exact patterning of the
secondary (blue/green) color is like a fingerprint; it develops
chemically rather than being set precisely by genetics. The
offspring of two 'spotted' discus will likely have spots, but not
in the exact same size/position as their parents.
S. discus
The Red Discus prefer very soft, acidic water with a 4.2–6.2 pH,
a water hardness of 0.0–1.0 dGH, and a temperature range of
26–30°C (79–86°F). Their native diet consists of a combination of
worms, insects, crustaceans, and plants. They originate from the
Negro River where it drains into the Amazon River and from the
Trombetas and Abacaxis Rivers.
S. aequifasciatus
The Blue Discus prefer soft, acidic water with a 6.0–8.0 pH, a
water hardness of 0.0–12.0 dGH, and a temperature range of
26–30°C (79–86°F). Their native diet consists of a combination of
insects and invertebrates. Besides their popularity among
aquarists, the fish are sometimes grown for food in subsistence
fisheries. The fish is natively found among rock crevices and
roots. They are a schooling fish except during the breeding
season when the become territorial. The Blue Discus originates
from the Solimões River to the Tocantins River basin.
