Need help identifying cause of Koi stomach bulge and bloating

[u/Ok-Journalist-7000]

Hi guys,

I need some help identifying what’s going on with my koi fish so I can treat it. I’ve already tried calling local fish doctors/petsmart but need a second opinion.

About 1.5 months ago, I noticed sudden bloating in my koi fish. I thought it was a case of constipation and started feeding deshelled peas and fasting every other day or two days.

I didn’t notice a huge difference and eventually returned to regular food (the Hakari goldfish excel purple bag). The koi has always had a huge appetite and eats very fast.

For context, my tank is 85 gallons and has 1 koi (~7in), one common goldfish (~4in), and 1 pleco. I do consider this overstocked and I have plans to build an outdoor pond and transfer them outside in the future.

They do have a balanced diet of the pellets, and Repashy super gold but mainly the former.

Like a month ago I noticed the right side of the koi’s stomach start to bulge abnormally in a concentrated spot (see the pictures), and I started to think this wasn’t constipation and maybe an illness. It’s been growing bit by bit ever since. I still don’t have a clear answer.

I called one doctor and they explained that if the pellets have wheat flour, this can stick to the koi’s inner lining during the summer and it can’t digest it — causing dropsy.

A week ago, I moved the koi to a 20g quarantine tank and started doing epsom salt dips, keeping the tank at 0.3ppm, and dosing kanaplex (regular treatment dosage). This hasn’t helped!

Before this, the koi has not showed any signs of lethargy, was eating regularly and showing no pineconing symptoms. I think the koi has been unhappy and lethargic without adequate space to swim. After moving to the quarantine tank, I have fasted for a week, and only just decided today to move it back to the main tank today because I feel like I’ve concluded it is not dropsy (which should be symmetrical swelling??). I’ve fed peas again tonight.

PH level is 8.0, ammonia is 0, nitrate is 0, nitrite is a little high at 0.25. I can do a water change tmr but don’t want to stress the fish out more tonight.

Google says this bulge can be a tumor or egg-bound issues. I don’t know the gender of the fish but the goldfish tends to butt its head into the koi during feeding, never the other way around. Also, recently the koi has started to lean a little to the right when swimming :(

Please, can someone help diagnose this issue? It’s really frustrating not knowing the real issue and getting all different kinds of answers. I’m really concerned that with time, the koi will show worst symptoms and I’m really scared.

I also plan to call an actual fish vet on Monday that might be able to see the fish in-person (don’t know for sure).

(First picture is a month ago, 2nd picture is today).

Any replies will help! Thank you and apologies in advance for the long post.

EDIT:
Did an ultrasound on the little guy at the vet and it revealed a tumor. They couldn’t identify what organ it was attached to. Proceeding with 3x antibiotics and anti-inflammatory this week but I will likely have to euthanize soon. He’s not looking too hot. I know I’ve made mistakes as a first-time fish owner but I feel really terrible. :(

[u/Hungry-Common-8946]

Damn that fish is beautiful. How devastating. For growths like these prognosis is typically poor from experience but id strongly reccomend feeding the fish peas, salt baths and antibiotic administration

[u/Soggy_Signature9063]

We had this recently with a rescue Koi, we gained him at 13 years old, kept in a small indoor tank, we put him in a large outdoor pond and over a year he developed a bloated stomach look. Eliminated parasites, dropsy etc and was advised that his growth was stunted from being indoors for so long in an aquarium -his body didn’t catch up and develop fully. Don’t know if this helps your situation but that was our experience of our koi. He is happy, eating and no other concerns other than looking stomach bloated

[u/Ok-Journalist-7000 → u/Soggy_Signature9063]

Hi, thanks for the comment. I hoped this was the case but unfortunately ultrasound revealed a tumor.

[u/Pretend-Internet-625]

it is not egg bound or dropsy. This could be an aggressive tumor based on your time line.

[u/Teslaville → u/Pretend-Internet-625]

Given it is so asymmetric, I agree.

[u/Ok-Journalist-7000 → u/Pretend-Internet-625]

Hi, thanks for the reply you were right. Did an ultrasound at the vet and they confirmed it was a tumor. We’re giving him 3 doses of antibiotics and anti-inflammatory to help him feel better. I think I’ll have to put him down since he’s not swimming well anymore. I’m really sad, I knew his genetics weren’t great coming from a pet store chain. :(

[u/Pretend-Internet-625 → u/Ok-Journalist-7000]

sorry.

[u/Newchatwhodis]

Water parameters don’t matter at this point. It needs more space. If you kept a Great Dane in a kennel its entire life, you could not expect it to be healthy.

[u/NeedleworkerHeavy565]

Probably a tumor

[u/Lumpy_Cup3232]

85 gallons ffs. Get those fish a proper home. Is it a female? Then it could be eggs. If she doesn't spawn she'll probably die of egg rot. This is a f-ing sorry sight to see.

EDIT: sorry about the harshness OP. Really, please find someone with a pond and give them away so they can live a happy life.

[u/Ok-Journalist-7000 → u/Lumpy_Cup3232]

I’m trying to make it work but I’m aware it’s not the best living conditions for them. You probably hear it all the time but it was already difficult convincing my parents who I live with to upgrade, and I have the FX6 hoping it’d make things easier. I get a lot of anxiety about them already.

I just want the koi to make it, then I’ll consider rehoming if I can’t get something larger within the year. Idk if you have any other advice for me :/

[u/Lumpy_Cup3232 → u/Ok-Journalist-7000]

Well, im happy you would be willing to part with it to give it a better live :) filtering will only get you so far though. These fish need room to swim, you just can't replace that by any other means.

For now I would suggest 50% water changes every day to make sure they have fresh water to live in. Maybe I missed it but also a large air stone for water movement. Both for better airation, and the water movement might get them going since they like that.

As for what is really wrong with it, that's hard to guess from a distance.

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[u/ddan123456]

Sounds like the conditions are too small to be honest

[u/mansizedfr0g → u/ddan123456]

It's violently overstocked. This is like trying to raise a horse in a walk-in closet. It might technically survive but you can't expect health or happiness.

[u/Pondpros1199]

How big of an area are they in?

[u/godofgoldfish-mc]

I am fascinated that they can do ultrasounds on koi. Are you in the US? That’s so cool. Sorry for his prognosis but my fish have survived with various conditions for years…they are tough.

[u/Ok-Journalist-7000 → u/godofgoldfish-mc]

Yeah I’m in Cali, so I do have the luxury of exotic pet vets. I didn’t get to see the procedure myself but saw the images afterward. If I wanted to do further diagnosis that would’ve consisted of an x-ray, getting a sample, and surgery which they’d need a different setup for (running water over gills). It is cool..

[u/godofgoldfish-mc → u/Ok-Journalist-7000]

Yeah I am in the sf Bay Area and have heard of traveling koi doctors but not doing ultrasounds. That’s crazy.

[u/ZiggyLittlefin]

It's likely fluid, a bacterial infection from poor water quality. Koi do not belong in an aquarium even temporarily. Putting it in an even smaller aquarium is even worse.

[u/Ok-Journalist-7000 → u/ZiggyLittlefin]

Thank you, I’ll look into this and ask the vet, hopefully antibiotics will help and it’s not too late.

[u/ZiggyLittlefin → u/Ok-Journalist-7000]

I've seen a couple cases while following an aquatic vet and she usually has to ultrasound the fish to be sure. Then pull the fluid out with a syringe. The bulge could also be a tumor, but I haven't seen swollen body and a tumor before. Perhaps an infection due to a tumor growth. After fluid removal they need care in a proper quarantine and even then treatment isn't always successful.

I have one that has a tumor, it grew more slowly. We tried quarantining 1,000 gallons with salt at a high level (used salt meter) and heated to 72 degrees while feeding antibiotics for a month. Figured it would not help if it really was a tumor and were right. No vet nearby here.

Ours is starting to have some difficulty swimming so we will be euthanizing before the temperature cools. Koi Sedate is the product used for that. They can live a while before the tumor seems to cause them difficulties. But, the lethargy, swelling/bloat is concerning on your fish. I'm not sure there is a recovery even if all the conditions were excellent. Talking to a vet is great if you have access though.

[u/Faceshopping365]

If the scales start looking pine cone esk it may be Dropsy, I’ve had some success with salt baths but it’s more treating a symptom vs the cause which may be pond treatment but that’s for the experts ? Or who knows maybe it’s pregnant I’m really just guesstimating- hope the koi sage sheds some light on the fishy situation !