More has been written about the Discus than any other tropical fish in the last 50 years, and it is now one of the most popular cichlids in the hobby, with many books devoted to it. This is intended to be a very brief general guide to its keeping and breeding within the aquarium.
When wild caught discus were first introduced into the hobby many years ago, they were a rare site, and thought very hard to keep. With time, experienced hobbyists mastered this aspect and the next step was breeding. Slowly people managed to get eggs, but they would never get successful fry. They key was leaving the fry with the parents, from whom they graze, eating their highly nutritious slime coating. Now discus breeding is common place, any thousands of colour strains have been produced, in addition to the many wild colour forms.
Discus are most commonly found in dense planting and wooded areas in slow moving rivers and backwaters in the Amazon river system. These waters are soft, warm and acidic, with little current. Their natural flat shape and colour pattern is designed to give camouflage in their natural home. They can usually be found in large groups, and when not spawning are mostly a social cichlids. Their natural food is comprised of aquatic inverts, insects, small fish and fry and any other naturally occurring food that may be available. Many other commonly kept south American tetras and cichlids can be found in these waters.
TEMPRAMENT, BEHAVIOR AND SIZE:
In case you need reminding, Discus are Cichlids! In the real world this means they are fishes of changeable behaviour, but also of character and personality. They can on occasion be aggressive towards their own kind and others, mainly when pair bonds are formed, or when territory of fry are involved. If some consideration is paid to this, in cichlid terms they are generally quite mild in behaviour.
The main problem is with bullying within themselves. Often, in small groups of fish the individual at the bottom of the pecking order is on the receiving end of a great deal of bullying, which can result in death. To avoid this, I would advocate not keeping the fish in groups of less than 4, with 6+ being an optimum, especially when young. This seems to spread the bullying out, and also increase the confidence of the fish.
Size wise, roughly 6-8″ round is a good side for an adult discus.
This is one of the areas that gives rise to the greatest amount of arguments between discus keepers, but this is what I feel is a good basic guide
- Water conditions for general keeping : pH 5.8-7.4 with 6.3-6.9 an optimum for most varieties. Water hardness is just as important as pH, a kH of 1-6 and gH of 2-11 being generally suitable. The fish may live in harder water, but for long term they need soft to medium water to thrive.
- Temperature : a range of 80-84 is acceptable, although many fish keepers use higher temperatures of up to 90f.
- Water quality : The higher the quality, the better! Tanks must be mature and stable, with 0 ammonia / nitrite, and nitrates and DOC’s as low as possible, with 20ppm an upper limit. Trying to keep the water as free of metals, phosphates and other contaminants will also help. Large weekly water changes are probably the order of the day.
- Filtration: Being big messy cichlids, efficient biological filtration is needed, but filtration that doesn’t produce too much current.
- Tank size : There are 2 main requirements, tank depth and volume. Because of their size and swimming habits, a minimum of 18″ is needed for tank depth, with deeper being better. Volume wise, a rough guide is that each adult discus will need 10 gallons of water. Larger tanks will also give more stable water conditions, and taking into account other considerations the minimum size for a discus display tank should be roughly 40 gallons.
- Feeding : A varied diet is the order of the day, this may include a high quality dried food up to about 50-60% maximum, which the discus will take with greed. Other foods should be insect fish based, such as frozen brine shrimp, blood worm, mysis shrimp, black mosquito larvae, chopped earth worm, prawns, chopped cockle etc. Discus can be susceptible to internal parasitic infections, so take care with live foods, and due to the fats / proteins its perhaps best to feed animal meant sparingly if at all.
- Tank mates : tank mates should be none aggressive fish that are not too active or skittish, and will tolerate warm soft acidic water. Dwarf south American cichlids, sucker mouth catfish, cory’s, tetras, rasboras, pencil fish among others will provide good friends for discus. Shoals of tetras or similar will act as dither fish, making the discus feel more safe in their surroundings
- Tank Set-up : Discus certainly don’t require bare tanks, and furnished display aquarium may even be advantageous. Tall planting round the back and sides of the tank, together with an inert substrate will limit the skittish behaviour of the fish. Bog wood and perhaps a little inert rock work will also be accepted, but the fish should be left large open swimming areas in the tank centre
Once many keepers have mastered keeping discus, their attentions often turn to breeding. While not being impossible, it can be hard work, but is also greatly rewarding. Like all cichlids, discus choose a spawning site then guard and rear the eggs and resulting fry.
- Sexing : Discus can be very hard to sex other than when spawning, and no reliable methods exist. A guide may be that males have longer fin extensions and a wider fore head.
- Pairing: Discus don’t take well to arranged marriages, so the best way to get a breeding pair in general is to by a group of young unrelated fish of the same colour type and let them pair up themselves. This may happen from when the fish are half grown, but generally spawning doesn’t start until the fish are roughly ¾ of their adult size. Once a pair is formed it will often remain for the life of the fish
- Spawning : Discus choose a near vertical smooth spawning site, which is cleaned before 80-400 eggs are laid by the female, and fertilised by the male. It takes 50-60 hours for the eggs to hatch, and another 36-48 hours for them to become free swimming, at which point the fry will start to graze of their parents. It may often take a few attempts for the pair to get it right, but two females can lay eggs and appear to be a pair.
- Breeding Tank : Breeding tanks are best kept simple, with simple air powered filtration, spawning sites (terracotta cones, broad leafed plants or slate) and no substrate. Water should be very soft to allow the eggs to develop properly, with excellent water quality and a temperature of about 84-88f. The tank need not be as large as the display tanks, but something of the order of 24x18x18 is certainly suitable.
- Feeding and conditioning : The parents will need a good and varied diet not just to condition them to spawn, but to provide nutrition when they are feeding their fry. Large water changes, a temperature rise and heavy feeding is often a good spawning trigger.
- Fry rearing: The fry do best when given additional feedings of small foods whilst with the parents, such as baby brine shrimp. After 3-6 weeks, the parents will be exhausted, and the fry growing fast so it is best to remove them. This is where lots of tanks and water changes are needed to achieve a decent growth rate. I used to grow circa. 40 fry to just under 2″ in a 55G tank, and this required heavy water changing. The discus market is saturated with fish, so it best to grow 20-50 excellent fry than 80 runts. Growth is reasonable, but not spectacular.
Although this is just a fraction of the information available, I hope it of help in some way. Enjoy the King of the Aquarium!
Picture and article by Chris Jewell.