My Swordtail has a bump growing on her head

[kmthw]

First of all, hello everyone. This is actually my first post.

Let me go straight to my problem since I am quite frustrated.

One of my female Swordtails has a bump growing on her head. It looks sort of like dropsy. This just started last night. I have attached pictures below.

She's still active and eating well. However, her fins is clamped most of the time. Her swim also looks different (kind of struggle swimming, using the whole body to swim, rarely using her fins).

Could you please help me figure out what going on with her? Is it really the dropsy? and how to treat her? She is one of my first fishes and I really don't want to lose her.

Here is my tank info.

55gal medium planted tank (no CO2, LED light)
36 fishes: platies, swordtails, rainbows, cory catfishes, many small tetras, some small danios.

Ammonia: 0
Nitrite: 0
Nitrate: 10-40 range, current read: 20
pH: 8
I don't have the Hardness test kit but I know my water is quite hard.

Weekly 20% - 40% water change with gravel vacuum (using Prime for pre-conditioning water)

Filtrations: Rena XP2 Canister + HOB rated for 55gal

This tank has been cycled for almost 9 months.

No fish, decor, plant added within last 3 months.

As I said before, this is one of my first fishes. So she's been with me for almost 9 months.

Diet: Spirulina flakes, API bottom feeder pellet, Hikari pellet for tropical fish.
Frozen brine shrimp and frozen blood worm are given once a week. No diet has changed for the last several months.

Please help my poor fish

 

[PWNE44]

need a better pic

 

[kmthw]

Here are some more close-up pics.

 

[kmthw]

Anyone ???

 

[Mebbid]

That is kind of strange. Is the spot still there?

 

[Darkseid76]

I suggest you isolate her. Dropsy usually gives fish the " pinecone" look.

I'm not sure there is much you can do without antibiotics. You should isolate her for treatment though.

I had a pineapple sword that died from same thing. Clamped fins, lethargic swimming, still eating. Tried my best but couldn't save him.

But definitely something wrong. Can tell just from photos.

 

[kmthw]

Thank you very much for your responses.

Now she is still alive and that spot is still there and I think it is a little bit bigger. However, the swimming issue seems to be a bit better. She is still active and eating well as usual.

What I have done with my tank so far is to reduce Nitrate to ~0 by changing water about 10% (No gravel vac) every 12 hours. Now my tank has 0 nitrate. I have not used any medication yet.

I just isolated her as you suggested into my 5 gallon.

Did you say I should use antibiotics? Could you please recommend which antibiotics I should use?

Also, since this could be bacterial infection, should I treat the main tank as well?

I hope I can save her.

 

[Darkseid76]

I can't recommend anything specific but there are treatments that involve specialty foods. The problem is ordering them and hoping they arrive on time. Bacterial infections are usually difficult to treat. No need to treat main tank unless as a last resort. Try searching the web up and see what you come up with. In the meantime maintain water quality in the QT and just keep a close eye.

 

[Darkseid76]

I found this old pic of a balloon Molly from over a year ago.

She was afflicted with something similar and never displayed any ill effects from it. I never figured out a treatment for her in time either.

 

[kmthw]

I will change 10% water daily. I am thinking about adding some salt also since she is a live-bearer.

Actually, I have some Anti-bacterial medications in hand which I've got since the beginning and they are not expired yet. Here are what I have.

Kanaplex (Seachem), Furan2 (API), and Pimafix/Melafix

I don't dare to use them yet since I don't know what's wrong with my fish.

Do you think I can mix Kanaplex with some pellet and feed her? or should I use or order something else like Clindamycin?

Thank you for your help and also for sharing the picture of that poor molly. My swordtail is not that severe yet and hopefully will not be, finger crossed.