If you want to breed Symphosodon Discus, it is important to start out with high-quality stock. The easiest way of obtaining a pair is to purchase a group of juvenile Discus and let them grow up together. Avoid stunted specimens where the eyes are too big in proportion to the body of the fish, since these specimens have not been well fed during their childhood, hence have not developed as they should. Go for proportional specimens with nicely rounded bodies and stay away from specimens that have mismatched fins or crossed fin filaments.
Water
Temperature
When Discus is introduced to a new home, keeping the water temperature high – up to 90 degrees F – is a good idea to prevent illness while the fish adjust to the aquarium. After about two weeks, you can let the temperature drop a few degrees, and after an additional two weeks, you can decrease it as far down as to 84 degrees F.
Chemistry
Discus hail from soft and acidic waters and will therefore appreciate such conditions in the aquarium. Wild caught specimens can need a pH in the 5.0-6.0 range and a GH of <1 degrees to spawn, while captive bred specimens tend to be more adjusted to harder and less acidic conditions and prefer a pH-value of 6.5-6.8 and a GH of <5 degrees.
Nitrogenous waste
Keeping the levels of nitrogenous waste down in the aquarium is extremely important when breeding Symphosodon Discus and vigorous filtration must be combined with frequent water changes. Many breeders actually change around 10-15% of the water once a day and 50% of the water twice a week. Uneaten food must be promptly removed from the water. The water used for water changes must be similar to the water in the aquarium to avoid chocking your Discus fish. Rapid changes in water temperature are particularly dangerous.
Feeding
Feed you Discus a varied diet to ensure optimal health. They love worms, e.g. bloodworms, blackworms etcetera. Feeding cones will prevent the worms from ending up all over the aquarium. Feed your fish a few times a day instead of one heavy feeding and make sure that they actually eat their food. Hunger strikes or poor appetite must be investigated and solved to prevent serious problems.
Discus behavior
Discus fish kept in groups will develop a pecking order. The dominant fish will for instance be able to feed before the more submissive ones get a shot at it and so on. Until everything is settled they can be quite aggressive towards each other. Once the pecking order has been formed, the amount of fighting and nipping will normally decrease drastically.
Discus Fish Spawning
As your Discus fish matures, they will hopefully start to form pairs. Once a pair has been formed, the couple will normally do a few “dry runs” before actually spawning. During the real spawning, the female will normally start by laying just a few eggs that are promptly fertilized by the male. She will then lay more and more eggs while the male is guarding the spawning site, and when he swims in to fertilize them, she will start guarding instead.
In most cases, the parents will be able to fend off other adult fishes and prevent them from eating the eggs. If the adult fishes are too strong and the parents too weak, you may however have to help out in order to save the eggs from ending up as food. Removing the non-parents from the aquarium is not a good idea, because not having anyone to fend off can weaken the pair bond between the parents and cause them to turn on each other or their offspring. You can instead use a piece of Plexiglas to divide the aquarium into two parts. This way the parents will still see the other fish and perceive them as a threat.
Parental care of fry
The eggs will normally hatch after 2-3 days at a water temperature of 84 degrees, and the fry will start feeding about 72 hours later. At this stage, the fry is too small to eat anything else than a special secretion produced on skin of the parents. The fry stay close to their parents and the parents will take turns caring for them. During the switch, the caring Discus will swim up to the other one and then rapidly dash away from the little cloud of fry. The fry will notice their other parent and commence feeding from him or her. The secretion is highly nutritious and within 5 days, the fry will have grown big enough to eat newly hatched brine shrimp. They will then continue to eat both brine shrimp and secretions.
Raising Discus fry
Many breeders chose to move the fry to a separate rearing aquarium before they are really weaned of their parents because the longer you let the fry stay with the parents the high the chance of the fry catching parasites from them. Adult Discus fish can harbor parasites without falling ill, but those same parasites can prove lethal for tiny fry.
In order to reach their full size, Discus fry must be provided with plenty of nutritious food and really low levels of nitrogenous waste. The work you do with young Discus will lay the foundation for their entire life. Feed the fry newly hatched brine shrimp three times a day and carry out a 50% water change every day. Within five weeks, they will be big enough to accept a wide range of foods, e.g. bloodworms, chopped up black worms and paste mix. The large amounts of food can easily foul the water and sometimes you might be forced to carry out water changes more than once a day.
Culling Discus
As your fry grows bigger it will be possible to notice birth defects and other problems. It is then time to start culling your fry to remove undesirable traits from the group. Do not hesitate to ask someone to help you with this, e.g. someone from your local aquarium club with extensive Discus experience, because spotting defects in really small specimens is tricky. If you want to cull your batch, you naturally want to do it as early as possible to avoid spending a lot of time, energy and space on raising defect specimens. By culling, you will be able to devote more space to the healthy ones, thereby giving them a better chance of survival and optimal growth. A few things to look out for in Discus are poor body shape, mismatched fins, crossed fin filaments, and eyes that are too large in proportion to the body.
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