Discus with indented/sunken belly but he is eating

hello everyone,
as the title explains I keep Diskus and one of them is behaving weirdly.
I’ve been reading posts on here about inflated belly’s and discus, but the causes never fit to mine.
Has has a really sunken in belly and the head itself is pretty thin aswell.
He is not bullied. Only the biggest 2 males fight a little here and there. The small ones and especially are not picked at.
So he comes to eat and the only thing you can notice is that he eats slower than the rest. But I feed enough for them to pick up food from the sandbed for around 10 minutes.
All the others are healthy, I even have a breeding pair in that same tank.
But now comes the weird part. He is in this state for close to 10 months now.every post or Thread is saying he should be dead after 2 weeks max. He eats, he has enough food around him, Artemia,mysis,Krill and clam meat every day.but he isn’t gaining any body volume. All of his brother have doubled in size by now.
What can I do? Is there something to help his belly?
He survived 2 tanks rebuilds and moving once.

Hi and welcome to the forum

What does its poop look like?

If fish go off their food and lose weight over a couple of weeks it's usually an internal protozoan infection. However, this has been going on for longer so that is unlikely to be the issue.

The fish probably has intestinal worms. See section 3 of the following link for treating fish with intestinal worms.

Discus bullying is different to other cichlids and there will be some bullying in the tank. There always is with Discus, especially if you have a breeding pair. They will pick on everyone and the stress and bickering goes down the line. The smallest weakest fish will stress, not eat properly and eventually dies. This could be part of the problem too (worms and stress).

It's a bit like a bully at school. They don't have to hit you to intimidate you. They can look at you, make subtle gestures, or say things. Discus are the same and very rarely bite each other but they do intimidate each other a lot.

Deworming the fish should help but if the fish continues to lose condition, move it to a different tank and see if it gets better. If it does better in another tank, then it was being bullied.

The best thing to do is to move it to another tank, it is stressed where it is at the moment.

itiwhetu said:

The best thing to do is to move it to another tank, it is stressed where it is at the moment.

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While I have no experience with Discus I used to do several types of other cichlids. Since the critter is distressed I would try to cause as little added trauma as possible.

This MAY be a dumb solution but I would put in a divider in the tank to isolate in the same environment as to which the critter is familiar. As to a divider a 1/4 inch plate of plexiglass with a bunch of drilled holes to allow water flow would work well. The plexiglass can easily be held in place with suction cups arranged on each side.

It would seem to me that this would isolate the critter without causing the added trauma of a totally new environment.

I don’t know how it’s poop looks like.

And to make my point clear, not a single other fish is hindering him at eating. He isn’t sitting in a corner , he isn’t scared to move to food. He directly sits in between all of the other discus and is eating with them. He is just slow and not gaining wheight.

I already tried to isolate him. This doesn’t work for discus.they stop eating without other discus around. I had him separated for a day and he didn’t care for any food.

I will look into the issue about worms and how to treat it, but aren’t worms going to affect my other fish aswell?

So I’m keeping my eyes open for poop now. I rarely see my discus poop,maybe they do it at night. I don’t see white poop laying on the ground atleast.
I looked up worms of all sorts and I think the symptoms of a flatworm fit the best.
The only problem is that most sources state flatworm lead to death within a few weeks aswell.
And most other worms are more likely to cause bell inflation.
Also the after of the fish doesn’t look special to me. Nearly all illnesses stated a slimy after as symptom.
I will add a video of them eating to show you he is fine eating with everyone else and not sidelining because other fish bother him in any way.
It’s so confusing, something doesn’t add up
Here the video of them getting their first meal of the day

And I watched the entire feeding, the big ones are pushing each other for space, the small one is literally air to the others. They don’t attack or behave any different when is directly next to them

Chronoloton said:

I will look into the issue about worms and how to treat it, but aren’t worms going to affect my other fish as well?

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Normally if one fish has worms, they all have worms.

In this case the smaller fish might have a lot of worms and the bigger fish only have a few. The smaller fish might have tapeworm and round worms whereas the others might only have round worms.

The smaller fish could also have gill flukes and might have a lot of them.

Treat all the fish for intestinal worms at the same time and see if it helps. Tapeworm treatment (Praziquantel) also kills gill flukes but start treating them for round/ thread worms first because it's more common than tapeworm.

Nice fish and tank.
Almost certainly internal parasites (worms), possibly in combination with reduced feeding from being the lowest in the group's pecking order. The fish is extremely thin, and shows typical razor-thin forehead, indicating malnutrition and generally declining health.
It does not have to be outright aggression on a fish, just substantially lessened ability to get to and eat food. But the fish almost certainly has internal parasites, and if that is the case, the whole tank should be treated (praziquantel is what I would use if available). Often times internal worms don't affect the fish too much, unless additional stressors (such as subservient status) also affect the fish.
The risk of not considering all fish having worms (which is unlikely as a cycle of having worms, pooping them or their eggs out, followed by reinfection is the typical situation) is that even if one isolates and brings back the currently ill fish, the lowest ranking fish in the new group will become similarly affected and so on down the line. Just about every time!

Another thing to notice is that one of the other fish in the photos (blue headed fish on lower right corner of 2 photos) has incipient HITH, although overall looks fairly healthy. Causes for this are hard to pinpoint without much additional info, but too high nitrates, low temperature, insufficient water changes and improper diet often are among the various culprits, alone or n combination. Sorry to rain on troublesome news, but inly recognizing what is going on ensures solving the issues.
Good luck!

At 11 seconds left on the video one of the big orange discus moves towards the little one and it moves out of the way pretty quick. That is the smaller fish being bullied by the bigger ones. The big discus only moves towards it a bit and it's only subtle but it's there in the video. So if it happens in a 30 second video, it is happening at other times too.

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If fish have a lot of worms, they can get fat around the belly but not always. If they only have a few worms they can look and act completely normally because the worms aren't take too much blood. The worms feed off the fish's blood and if the fish only have a few worms and the fish are well fed, they can tolerate losing a little blood each day. But if the fish isn't eating as well and has lots of worms, it will lose weight and end up dying. Bigger fish can tolerate more worms for longer than smaller fish can.

The more food the fish get and the higher the quality of the food, the longer they can live for with the worms. The fewer worms they have, the longer they can live too. The worms don't want to kill the fish because they die too. They are parasites that feed off the fish and want it to live forever so they can live forever. I have had fish live with thread/ round worms for over a year and they survived because they were fed really well.

A slimy appearance on fish is usually caused by poor water quality or an external protozoan infection. Worms don't make fish look much different on the outside unless they have sucked most of the blood out of the fish. Then they look like the little discus.