What is lump on Molly Sailfin Head? Cancer? Bite?


What is the water volume of the tank? 80 Gallons
How long has the tank been running? Since 11/6/2021
Does it have a filter? 5 Sponge and one HOB
Does it have a heater? 500 Watt
What is the water temperature? 78.2
What is the entire stocking of this tank? (Please list all fish and inverts.)
4 Corydoras
3 Lyretail mollies
2 Sunburst Platies
2 Black Sailfin Mollies

How often do you change the water? Biweekly
How much of the water do you change? 20 to 25 gallons
What do you use to treat your water? Prime
Do you vacuum the substrate or just the water? Vaccum Sand twice per week

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes
What do you use to test the water? API Master Kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Nitrate:5 PPM
pH: 7.6

How often do you feed your fish? Once per day
How much do you feed your fish? About 4-6 flakes per fish
What brand of food do you feed your fish? Tetra tropical flakes
Do you feed frozen? Blood worms
Do you feed freeze-dried foods? Shrimp pellets for corys

Illness & Symptoms
How long have you had this fish? One Year
How long ago did you first notice these symptoms? 1 week
In a few words, can you explain the symptoms? Noticed a raised bump dead center on head. Thought it was a nip, but it is growing rapidly.
Have you started any treatment for the illness? Quarantine
Was your fish physically ill or injured upon purchase? Yes, had respiratory issues treated 2 months ago with antibiotics and paracleanse, successful outcome.
How has its behavior and appearance changed, if at all? No behaviorial changes noted.

Explain your emergency situation in detail.

Please help, my Molly has a growing lump on his head.
About a week ago, I placed a male Lyretail molly in tank, fighting ensued. After battle, I noticed a small bump on Black Sailfin Molly's head. I thought he was nipped, but the bump has increaded in size and now it looks like a tumor. Today, I removed the Black Sailfin Molly, and placed him In QT with super clean water, heater and gravel substrate (needed it to cycle QT tank), and fully cycled sponge filter for 15 gallons. He is pretty mad, missing his tankmates. I won't breed him now due to his possible genetic predisposition to tumors. Please review the photo and provide any much welcomed advice. Thank you for all your help.


Hi there. :)
Any way you could capture some better pictures? I feel like a good visual is the only way to tell what’s going on..

I find that turning all the lights off in the room except the tank light helps a little..


Thank you, JuDom. I hope these photos are better. He hates to have his picture taken but loves to come to me. Sorry it's taking so long to get a decent pic. Hope this shows a fleshy, flesh colored bump.


I’m not familiar enough with tumors on fish to tell you that that’s what it is.

As per your original post, you stated he had been in a scuffle prior to the bump arising. Due to him recently having been on antibiotics, it’s very likely that his immune system was still in a weak state and therefore a small injury could cause more damage than usual.

Is his behavior still the same? Is he eating normally? I’m sure being in QT has him a little spooked.


thanks for responding, JuDom. Yes, he is chasing females, eating like a pig and acting as normal as ever. No changes in his daily routine.
Since I put him in the QT, he doesn't act as animated, he's not happy away from his gals. LOL


How’s your Molly doing today?
Any changes?


Hello JuDom, I'm treating him with some Melafix, I believe it is a bite injury, as you thought it might be. I only use it for mild injuries that need a little help. He's still not happy about being in the tank, LOL. The "nip" has already started to heal. Thank you so much for your help. I appreciate it so very much. Have a great night!


You're quite welcome. Glad to hear that he is on the mend.
Good luck reacclimating him to the community tank when the time is right, I'm sure he can't wait to get back to his ladies ;) LOL

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