A Discus Display
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 Amazon basin.

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) ramirezi or

1 male + 3 females of your favorite Apistos Apistogramma sp. or

1 male + 3 female Checkerboard Cichlids Dicrossus filamentosus, etc.

Because of the temperature and low pH, the choice of plants is rather limited:

1 - 2 Amazon Sword Plants Echinodorus parviflorus (doesn't get too large)

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!?