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De-worming and Discus bloat


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Nov 11, 2019
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I have 6 discus ranging from 9-14cm. The tank is 165 litres, I'm going to upgrade them within the next 3 months.

The smallest guy has a very thin head and body, and one of the bigger guys has bloat. I have used
Epsom-salts twice now and neither fish seem to be improving. I used 10 teaspoons. I think it could be some kind of parasite or infection.

I have 4 tanks 165-220 litres. All of the other tanks are doing well. I do not test the water. I just add stuff to get rid of the chlorine. I know I should test it and try to aim for the certain parameters but I would rather have it constant than trying to get the ideal.

Can get photos of fish if needed.
Apr 29, 2012
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Hi there. I'm sorry that you haven't had any replies yet, hopefully a more knowledgeable discus keeper will come along, however I have kept them before and I know a little bit. First off, that tank is way too small for discus, even if temporary. I think that anyone who knows about them will tell you this. You most likely know that they are very sensitive fish, and even if your water parameters are prefect on paper, they could be easily stressed from being kept in that small of a tank, leading to all kinds of problems. I once had a pair in a 200L, and as they grew, that tank just became way too small for them really. You will hear different advice from different people, but I often hear that 200L is the absolute minimum to have one/two discus, however just going by past experience, I wouldn't keep any in anything less than 300L, ideally 350L and up. They really do need lots of open space to swim, and one of mine grew to over 16cm.

I think that before anyone can answer your questions, you need to post your water parameters, especially water temp, GH, PH, nitrate, etc. Is that tank bare, or does it have substrate/gravel? How often are you doing water changes, and how much water? Are there any other fish in with them? If some of them are only 9cm then they fully grown yet, so they are either much younger than the larger ones, or they are stunted (which will happen if they are kept in that small a tank). Did you get them all at the same time, and where did you get them from (breeder, shop, etc.)? Are they all eating, and what and how much are you feeding them? This may seem like a lot of questions, but it's all very important to know before anyone can help you diagnose anything with your fish.


Jan 26, 2008
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Perth, WA
This is probably too late for the skinny discus but the following information applies to this discus issue as well as any fish that produces a stringy white or clear poop. In this case, I would use Metronidazole first and then deworm all the fish.

Before treating any fish with medication, do the following:
Wipe the inside of the glass down with a clean fish sponge.
Do a huge water change (75-90%) and complete gravel clean. Make sure new water is free of chlorine/ chloramine before it's added to the tank.
Clean the filter if it hasn't been done in the last 2 weeks.
Remove carbon from filter.
Increase aeration/ surface turbulence.

1) Internal Bacterial Infections causes the fish to stop eating, swell up like a balloon, breath heavily at surface or near a filter outlet, do stringy white poop, and die within 24-48 hours of showing these symptoms. This cannot normally be cured because massive internal organ failure has already occurred.

2) Internal Protozoan Infections cause the fish to lose weight rapidly (over a week or two), fish continues to eat and swim around but not as much as normal, does stringy white poop. If not treated the fish dies a week or so after these symptoms appear. Metronidazole normally works well for this.

There is a medication (API General Cure) that contains Praziquantel and Metronidazole and might be worth trying.

It's interesting that API and the Californian government have listed Metronidazole as a carcinogen. That's a concern considering it was widely used to treat intestinal infections in people.

Anyway, handle with care, don't inhale the medication, and wash hands with soapy water after treating the fish or working in the tank.

3) Intestinal Worms like tapeworm and threadworms cause the fish to lose weight, continue eating and swimming normally, do a stringy white poop. Fish can do this for months and not be too badly affected. In some cases, fish with bad worm infestation will actually gain weight and get fat and look like a pregnant guppy. This is due to the huge number of worms inside the fish.

If the fish are still eating well, then worms is the most likely cause.

You can use Praziquantel to treat tapeworm and gill flukes. And Levamisole to treat thread/ round worms. If you can't find these medications, look for Flubendazole.

Remove carbon from filters before treatment and increase aeration/ surface turbulence to maximise oxygen levels in the water.

You treat the fish once a week for 4 weeks. The first treatment will kill any worms in the fish. The second, third and forth treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.

Treat every fish tank in the house at the same time.

You do a 75% water change and complete gravel clean 24-48 hours after treatment. Clean the filter 24 hours after treatment too.

Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.

The water changes will remove most of the medication so you don't overdose the fish the next time you treat them. The gravel cleaning will suck out any worms and eggs that have been expelled by the fish. Repeating the treatment for 3-4 doses at weekly intervals will kill any worms that hatch from eggs. At the end of the treatment you will have healthier fish. :)