By Uncle Bill
This is an article on small aquaria. Although far more critical and
less forgiving than large displays, due to their small volume of water, a
very attractive and satisfying microcosm can be created. As much as I
prefer to attempt to recreate conditions as close to the natural environment
as possible, you won't want to do that with a discus tank. It
would be ugly. Just a muddy bottom covered with rotting leaves and some
branches hanging into the water. So, instead of a biotope aquarium we'll
do a geographic display. At least the plants and fish will be from the
I've often heard hobbyists say that they would love to keep discus but
they can't afford all of the necessary equipment, the large tanks, the
special foods, filters and, besides, they don't know enough about really
delicate fish to attempt to keep them. Let me put all of those
misconceptions to rest once and for all. Sure discus have gotten a bad
reputation for being difficult because people try to "acclimate"
them. Fish, as a general rule, don't "acclimate" without stress.
Stress causes the weakening of the immune system and, if continued for an
extended length of time, will ultimately end with the death of the animal.
It will probably be diagnosed as having had intestinal parasites, a
systemic bacterial infection, "hole in the head" disease or any
number of ailments. The real cause of death was stress and the disease (dis-ease)
was merely a symptom of that stress. We as hobbyists must remember that we
don't keep fish; fish keep fish. We keep water! We are aqua-rists, not fish-arists.
Before setting up the display, it is important to determine the strain
and the source of the discus to be featured. If you want to feature wild
fish then the species and the area of capture are very important. While we
hear that all discus come from extremely soft and acidic water, the
quality of that water varies depending on the specific river system or
lake. This will also help to determine the appropriate tank mates for your
setup. If the chosen discus is to be a colorful, commercially bred strain,
such as Jack Wattley's Turquoise Discus, attempt to contact the breeder
and get the temperature, pH and hardness of the water in the breeding
facility. You will be doing yourself and your pet a big favor by just
doing this one little bit of investigation prior to setup.
Personally, I quarantine any and all fish for at least one month
prior to introducing them to their new home. This is the safest way to get
your fish comfortable and eating well while you take the necessary time to
relieve the stress if its recent ordeal and observe it for any signs of
disease. Many ailments will not become apparent for two to three weeks,
and without a proper quarantine period, a potential disaster (and a real
headache for you) can be introduced to otherwise healthy tank mates.
Another thing that's overlooked by most hobbyists is the actual volume
of water in their aquarium. For this Discus Display we'll use a "20
gallon (77l)" tank. This is an absolute minimum for housing one and,
yes, only one discus. First, we'll measure a standard 20 gallon tank and
then you'll see why. A "20 gallon aquarium" does not contain 20
gallons of water. At least I've never seen any commercial aquarium that
holds the amount of water that is advertised. I've always wondered why
they made the computer monitor manufacturers disclose the actual viewing
area of the screen and they don't require that aquarium manufacturers disclose the actual volume of water contained in an aquarium. What ever
happened to truth in advertising? If you would like to know the actual
amount held by your tank, here is the formula: Length x Width x Height
(measure internal dimensions in inches) and divide the result by 231. Here
is an actual example of a standard "20 gallon (77l)" tank that I
have in my fish room: (inner dimensions) L 23.5" x W 11.5" x H
16" = 4324 ÷ 231 = 18.72 gal. For a metric conversion (cm), multiply
inches by 2.5 and for liters, multiply gallons x 3.85. Next we must allow
for 1"+- at the surface for gas exchange and another 2" (5cm)
minimum for a substrate. Now the dimensions are: 23.5 x 11.5 x 13 = 3513
÷ 231 = 15.2 gallons (58.52l). Add a piece of driftwood and a few rocks
and you have 14+- gallons (53.9+-l). There is barely room for one discus.
If you change 40% - 50% of the water each and every week, maybe, just
maybe we can add a few more fish for interest. It is important to remember
that the tank mates to be chosen are native to waters with a temperature in
the 84° - 86° temperature range.
Compatible dither fish would be:
6 - 7 Cardinal Tetras Paracheirodon axelrodi or
5 - 6 Rummynose Tetra Hemigrammus blehri, H. rhodostomus or
5 - 7 Pencilfish Nanobrycon sp., Nannostomus sp. (depending on
adult size) or
6 - 7 small Hatchetfishes Carnegiella sp., etc.
All of the above tetras are schooling fish and can be found in very
soft and acidic water. For bottom fish I like to use Dwarf Cichlids rather
than Corys Corydoras sp. as they are usually found in waters less
acidic and not as warm as those that Discus inhabit. The same holds true
for the Neon Tetra Paracheirodon (Hyphessobrycon) innesi.
The following are some appropriate small cichlids:
1 male + 3 female Ram Cichlids Microgeophagus (Papiliochromis)
1 male + 3 females of your favorite Apistos Apistogramma sp. or
1 male + 3 female Checkerboard Cichlids Dicrossus filamentosus,
Because of the temperature and low pH, the choice of plants is rather
1 - 2 Amazon Sword Plants Echinodorus parviflorus (doesn't get
12 or more: Alternanthera sp. make a colorful (burgundy red and
olive green) contrast to the Sword Plant(s)
These plants require lots of Full Spectrum lighting so purchase
a florescent hood for two 24" bulbs. The only filter necessary for
this display is a small "hang on the back" power filter because
you are going to change 50% of the water each week - Aren't You!?