Setting Up the Discus Aquarium and Induce the Fish to Spawn
Last month we looked at Discus varieties and the water conditions preferred by them. Now let us consider the aquariums to hold these regal fish.
There are two popular ways to set up your tank: the natural or aesthetic set-up, or the hygienic, sterile set-up.
If you are intending to position your aquarium in your lounge you will probably have great difficulty persuading your spouse that a virtually bare tank is pleasing to the eye in this location! In these circumstances, the natural system will be your only choice.
Ideally, I would recommend a 48" x 18" x 15" aquarium as being the most suitable for housing 6 - 8 young Discus with enough "room" to grow them on to maturity.
Choice of filtration is really down to your own preference with the natural system. Undergravels, of course, remain the most popular although power filtration is equally suitable, with one proviso: Discus, as indicated by their shape, come from slow flowing, almost still waters. If you decide to use power filtration, please use some method of diffusing the flow, as you will otherwise only stress your fish, which could lead to other problems.
Having decided on your filtration, next choose your substrate. In my previous article I stressed the importance of providing Discus with soft water. There is no point in going to all this trouble and then using ordinary gravel, which will dissolve into your water, and thus raise the hardness. Make sure you select a substrate that is inert - a flint based gravel, or maybe Hortag or similar. Any good dealer will advise you.
A simple test to determine whether or not your gravel is suitable is to place a small amount in a phial and add vinegar. If there is no reaction it is more or less safe to assume that you medium is okay.
Decorate your tank with bogwood, well soaked to remove humic acids, which could lead to acidosis. 'Instant Amazon' (Technical Aquatic Products Ltd.) in a controlled dosage will give ideal black water conditions.
When selecting plants for this aesthetic aquarium, be sure to choose only those that will tolerate the higher temperatures required by Discus (84°F - 86°F).
If this type of set-up is adopted, it is probably advisable to add a small shoal of Corydoras catfish to your tank; these fish will consume any food that your Discus do not eat. Discus are prone to suffer from diseases caused by bacterial loading in your tank, brought about by decomposing food and faeces. This is why I prefer the hygienic set-up where the tank is almost bare with no substrate. Any uneaten food or faeces can easily be observed and siphoned out daily, thus avoiding bacterial problems.
My own tank is a 48" x 24" x 24", in which I am bringing on some young Schmidt-Focke Brilliant Turquoise Discus. The tank itself is completely bare except of course for a heater stat and part of the filtration system.
I have constructed my filter thus: in the tank itself I have a plastic cat litter tray, the bottom of which is totally covered by Rena U/G plates.
On the uplift I have fitted a power head from which a pipe feeds the water up to a plastic seed tray, suspended above the tank. This acts both as a trickle filter and also, as previously discussed, reduces the excessive flow generated by the power head.
The medium I use in both filters is Hortag, a fired clay product which is totally inert. If you desire, a plastic plant may be inserted into the Hortag for aesthetics and to provide cover for the fish themselves.
Additional chemical filtration can be achieved using a high quality, marine grade, activated carbon and ammonia remover in an external power filter with its spray bar directed into the overhead trickle filter, again diffusing the flow.
Before leaving the subject of filtration, please remember that any filtration system is purely mechanical when first installed. It does not become a living biological filter until the nitrogen cycle is complete. I do not propose to cover the nitrogen cycle again, as this has been covered many times previously in Practical Fishkeeping, but I would like to contribute a few points which may be helpful to you, not only concerning Discus, but any aquarium (including marine). It is far better to artificially induce the nitrogen cycle by using a product like 'Establish' (Technical Aquatic Products Ltd).
Why? As far as I am concerned, it is wrong to submit any fish to high levels of toxic ammonia (NH³) or nitrite (NO²), even if the fish is considered to be nitrite (NO²) tolerant. Discus are very susceptible to levels of nitrite (NO²) above .05ppm (mg/l).
NEVER put Discus into a tank that has not been matured! Another benefit of using a maturation agent like 'Establish' (TAP) is that the resulting colony of desired bacteria (i.e. Nitrosomonas and Nitrobacter) is far superior to that created by seeding or using fish, as the potential for colonies of useless heterotrophic bacteria is greatly reduced.
The result is an efficient filter bed capable of supporting more fish without any problems from ammonia or nitrite. The drawback is the fact that this cycle takes approximately four weeks to complete, and unfortunately most hobbyists (in particular new ones) do not have the patience to have a tank devoid of fish for this period of time. If only we could adopt this practice, the so called 'New Tank' syndrome would cease to exist!
Now to get back on course. Assuming that we have a tank of suitable dimensions containing soft, acid water (0 - 4 dGH) with a pH of around 6.5 maintained at a temperature of 84° - 86°F, not forgetting, of course, our mature filtration system, we are now ready to purchase our fish.
Discus are not easily sexed, even when adult, and as they are a shoaling fish it is therefore prudent to buy six to eight individuals of whatever size and variety your wallet will stand.
From about eighteen months of age your fish will have developed into full colour, and at a size of four inches plus, your fish may show signs of pairing. This follows the normal cichlid pattern, two individuals separating from the shoal and indulging in jaw locking etc. Plus you will witness the pair bowing to one another. Now is the time to introduce an eight inch flowerpot or a spawning cone into the tank and hold your breath!
It is probably best to remove the other fish from your tank at this stage. If the prospective pair are netted out, it is likely that breeding behaviour will be disrupted for several weeks. The breeding tubes of the fish will by now be visible and an accurate decision can now be made about the sex of each one.
The tube of the male will be pointed, while that of the female is slightly broader and flat at the end.
Using the inverted pot or cone as a spawning site, the female will proceed to lay her eggs, each row being immediately fertilised by the male. When spawning is complete, both parents tend the eggs, fanning them and removing any infertile eggs.
Do not be alarmed if your fish adopt a darker hue at this stage, as it is only a mucus developing on which the fry will shortly be feeding. After 2-3 days the fry will hatch, and then in 4-5 days will become free swimming. It is now that the magical sight of the brood of young, swarming on the flanks of the adults and feeding on the mucus secretion, can be seen. It is extremely difficult to rear the fry away from the parents, but as long as they have been feeding on the mucus for about a week, it can then be possible to continue rearing them using alternative foods.
Next month I intend to help you choose the right nutritional food for your Discus and reveal how to combat and avoid disease. I shall also reveal to you the cure for 'Hole in the Head' disease, the undoing of many Discus keepers.
©Max Pickering 1999
