Misgurnus anguillicaudatus with lump?

Question
Hello Susan,

I hope you can help me.

I have Dojo Loach (Misgurnus anguillicaudatus). He is roughly 1.5yrs old so rather young for his species as I have another that is around 8yrs old.

For the past month he has had localized swelling around his abdomen. I thought maybe it was constipation but it steadily got worse til about a week ago when it stayed the same. The best way to describe it would be that he looks heavily pregnant but he is most definitely not. In the past 24hrs it has drastically worsened and now he seems to have internal bleeding (this is a guess, he is of the Golden kind so his skin is partially transparent and this morning it appeared as though blood was clotting under the skin in a very small area), though he is still feeding and swimming like usual and seems happy despite his massive bloating. Water quality is great and temperature is at 23. Ammonia and Nitrites both at 0. Nitrates at 10
There are no other symptoms. No flukes, sores, cuts or an inflamed anus.

He seems ok but it is very hard to watch him slowly swell; it looks so uncomfortable.

One other thing (which I'm not sure will help but) the swelling is expanding outwards and movement of it up through his abdomen is minimal. it is very localized. It also seems more boil/fluid-like than tumor-like as it flattens when he is pressed against the glass.

I hope you can help as I have been considering euthanasia recently which I would prefer to avoid. I don't even known what it could be! Thats the most frustrating thing!. I've dealt with bloated-fish style diseases in the past but I have never seen this kind of thing before.

Bacteria? virus? organ failure? I can't decide where to begin!

Answer
Hi rachel,
I'm sorry to hear about your dojo loach....
I've experienced quite similar symptoms with the swelling in quite different species of fish. It was a large oscar cichlid, he gradually developed a somewhat fluid filled lump in his lower belly that gradually grew even though he would carry on as normal. I could never find an accurate diagnoses even when seeking help from others.  I had to eventually humanely euthanize him.

Unfortunately when encountering mysterious symptoms like this in fish without medical tests and procedures an aquatic vet would preform we can only make an educated guess. My first thought is it could be a cyst. Sadly there isn't much that can be done about this. It may even burst on its own and may or may not kill the poor fish. It may continue to grow until it interferes with organs in the fish's body.

The best thing to do is keep a close eye on him as I know you will, and if he starts behaving stressed then the best thing would be euthanasia. Thankfully there is a humane method I've used before called "the clove oil method" a simple search should yield you the info you need should that time come. I wish I could bring better news but at least he has the privilage of such a kind and caring owner.

Best of luck Rachel,
I hope this helps
Susan~