Female Blue Platy Has a Lump on Right Side

I have a blue female platy and have had her for a year. She is living in a 20 gal tank with 7 of her babies (they are in the fingerlings life stage now) and 1 male molly. The tank parameters are great, no ammonia, no nitrites, and nitrates around 20 ppm. The tank is due for a water change this week. A few days ago, I noticed that she has a lump on her right side. When you are able to look at her head on, it is very apparent that there is a lump on her right abdomen area. I have been meaning to research and look into what could cause a lump in that location and what, if anything, I can do about it, but I have not had a chance to do any of that. So, I'm just wondering if anyone might know what the cause of the lump is, should I worry about it, and if I can do anything about it. She is eating just fine.

I have not been able to get a good picture of her to share, but will keep on trying. Any help would be greatly appreciated.

Sometimes fish get benign growths. People too. As long as she's eating and acting normally, I'd say don't do anything drastic or add medicines or anything. It may go away on its own

Look up lymphocystis. It's virus, there is no treatment if that's what it is. Fish can live with it & it may go away but it can come back or spread to other fish.

The most noticeable symptom of lymphocystis is the appearance of small, wart-like growths on the fish's skin and fins. These growths can vary in size and color, but they often look like tiny cauliflowers.

need pictures of the fish clearly showing the lump.

I agree on what Colin says... Pictures may tell a lot more...

Here are some photos that I was able to get just now of my female blue platy. The lump looks to be internal and not external. As I said, she eats just fine and is acting like her normal self.

Should I quarantine her? I have a 3 gal cylinder tank that is established (she used to live in it) that she can go in and not infect the other fish if it is a virus.

It's not a virus and you don't need to move her. She is either slightly lopsided due to being gravid (pregnant) or she has a growth in her. You can't treat internal growths and you leave the fish until it has trouble swimming or stops eating then euthanase it. In this case I would say it's probably more likely to be babies inside her. Monitor and see how things go. If it's still there after she gives birth, then post more pictures. If it is still there after she has given birth then it's almost certainly an internal tumour.

Colin_T said:

It's not a virus and you don't need to move her. She is either slightly lopsided due to being gravid (pregnant) or she has a growth in her. You can't treat internal growths and you leave the fish until it has trouble swimming or stops eating then euthanase it. In this case I would say it's probably more likely to be babies inside her. Monitor and see how things go. If it's still there after she gives birth, then post more pictures. If it is still there after she has given birth then it's almost certainly an internal tumour.

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Thank you for your help and advice. I've seen her pregnant before and there was never a lump sticking out like that before. Maybe it is due to her being pregnant. I have a male adult molly that is always following her around. Or maybe it is a tumor and just watch her until she can't swim or declines rapidly. I guess only time will tell. I'll just watch her and go from there.

I'll post pictures if anything changes.