Discus Nutrition in Fry

The ability of discus fish to properly digest and utilize nutrients begins very early in life. If discus fry do not get a proper start with their diet, they can run into problems when they approach the two-inch size. At this time they can become impacted, and can swell up until they actually die. This information is so important that I was torn between placing it in the breeding section, nutrition section or health. I have decided to place it here with references to it in other areas.

In the development of discus fry, the stomach and digestive tract (gut) is very short and small at the time of free swimming. This is perfectly suited for the nutrient rich soft diet of the slime coat provided on the sides of the body of mom and pop. With the addition of artemia (new hatched baby brine shrimp), the stomach of the fry changes. This is because of the roughage now provided in the diet. Quite simply the artemia needs to travel through a greater distance of gut to be digested. Artemia is a drastic diet change from the soft nutrient loaded slime coat the fry have been eating off the parents’ bodies. The drastic diet change requires drastic changes in the discus gut to enable the fry to properly digest artemia. The gut of the discus fry grows and becomes three to four times as long as the body length by three months of age. Then gut growth slows down and an adult discus has a gut length of around one and a half times the body length.

If the discus fry is removed from the parents and placed on a diet that is very low in roughage, that short gut never develops properly. This is seen in discus that have been artificially raised on a really soft diet with little roughage. What can occur is problems develop when the juvenile discus is between two to two and a half inches. At some point these discus find their way into discus hobbyists aquaria, and are placed on a proper diet that contains roughage. Feeding a flake food or pellets made from coarse fish meal (a lousy, cheap discus diet to begin with) really can be a problem even with discus used to roughage in the diet. So a hobbyist has a discus that suddenly swells up like a balloon. Nothing seems to help. The poor fish just swells until he dies. Why? That tiny little gut can not digest the food. So it sits there in the gut, producing gas and as bacteria begin multiplying in the putrefied food, serious symptoms develop such as cloudy eyes, membrane problems, loss of balance and an extremely distended abdomen. To the inexperienced hobbyist, they decide the discus has internal parasites along with a serious bacterial infection in the slime coat and eyes. They treat accordingly, the fish die and the hobbyist goes away inaccurately convinced of what killed the discus.
Discus fry that are artificially raised, and never see artemia, and instead are fed with soft artemia substitutes are prime candidates for this. This may not be how you expected me to kick off the section of this book dealing with nutrition. Like I said in the beginning, I am not holding anything back. As more and more artificially raised imported discus are flooding the market, this has become a major epidemic. A simple change in the diet by the breeder would prevent this. If a discus is really swollen in the abdomen, move it to a smaller tank such as a ten-gallon size with established bio filter and slowly rehab the fish, beginning with a treatment for constipation followed by a change in the diet to foods with less roughage, such as frozen blood worms. After rehabbing the fish avoid feeding all type pellets and avoid flakefoods composed mainly of fish meal and never use freeze dried foods with discus.