If I had a discus fish not eating or only picking at its food, I would consider it a red flag that something was wrong with its health. Recognizing the symptoms early and knowing how to address them can make a big difference in the health of your discus fish. Here is what I would look for and how I would try to help the fish regain its appetite.
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1. Check for Signs of Hexamita or Parasites
One of the first things I would check is the color and consistency of the fish’s feces. Healthy discus fish normally produce brown or black feces, depending on what they have been eating.
White or stringy feces, especially when the fish has stopped eating and is losing weight, can indicate a parasitic infection such as Hexamita.
Hexamita is commonly associated with hole-in-the-head disease and can affect many cichlids, including discus. The parasite lives in the intestines and takes nutrients from the food your fish eats, eventually causing malnutrition and weight loss.
An infected discus may continue eating and swallowing its food normally at first. However, the parasites inside its digestive system feed on that food, preventing the discus from getting the nutrition it needs. As the infection continues, the discus slowly loses its appetite, becomes thinner, and gradually fades away. In my experience, this can take three weeks or longer. The discus may also turn dark (except for pigeon blood discus), usually stays still, faces the back of the tank, and refuses to eat.
2. Treating Hexamita
One effective treatment for Hexamita is metronidazole. This medication helps eliminate certain internal parasites and can be given through medicated food or added directly to the aquarium water.
If the discus is still eating, adding the medication to its food may deliver it directly to the intestines, where the parasites live. When the discus eats the medicated food, the parasites also consume it and die. That’s why, if you can get the discus to keep eating the medicated food, it has a good chance of surviving.
Always follow the dosage instructions carefully and monitor how your fish responds to the medication.
If your discus has stopped eating completely, medicated food won’t help. In that case, see my guide on treating discus parasites with heat, which I have used as a last resort.
Along with the medication, maintaining good tank conditions is very important. Keep the water temperature and pH suitable for discus fish. The temperature should generally be around 82°F to 86°F, with a pH of approximately 6.5 to 7.5. A reliable heater, a thermometer, and a test kit will help you keep them steady.
Regular water changes and tank cleaning are also important when treating Hexamita and other parasites. Treat the new water with a conditioner such as Seachem Prime.
3. Encouraging Your Discus Fish to Eat
If your discus survives the infection but is still reluctant to eat, try tempting it with live food. Live blackworms and live brine shrimp are excellent choices.
The movement of live food can trigger the discus fish’s natural feeding instinct and encourage it to start eating again.
If you cannot get your discus to eat, it will eventually waste away and die. In my experience, a discus can go without eating for around three weeks or so, but I would not wait that long before doing something.
In the old days, about 40 years ago, I force-fed a discus that would not eat, and the fish survived. However, force-feeding is something you need to know how to do, because you could injure the fish if it is done incorrectly.
4. Gradually Return to the Regular Diet
Once your discus begins showing an interest in live food, gradually reintroduce its regular diet, such as quality flake food. Do this slowly so the fish can adjust without additional stress.
Start with small amounts and make sure the fish is actually swallowing the food. Remove any uneaten food so it does not spoil and affect the water quality.
Conclusion
Having a discus fish not eating can be distressing, but recognizing the symptoms early and taking action can help the fish recover.
Pay close attention to changes in its eating habits, feces, color, weight, and behavior. A discus that turns dark, faces the back of the tank, produces white stringy feces, and refuses to eat may be suffering from Hexamita or another internal parasite.
Metronidazole, clean water, and proper tank maintenance can help treat the problem. Once the fish begins recovering, live blackworms or live brine shrimp may encourage it to start eating again.
The sooner you recognize the symptoms and begin treatment, the better the fish’s chance of recovering.
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