Cory help

[Never too many fish]

Does anyone know what this spot is on the front fin where it attaches to her body. A few more also have it.been there 7 or 8 weeks. Water is fine. Tank was started about a year ago. 20 gallon tank with 7 corys, 3 ottos and a few platys. It is raised like a cyst and red around it. Have done 2 ick teatments, tried polyguard, melafix and a low dose of salt. Nothing has taken them away.

 

[MattW]

I’m not 100% sure but other members will have a better idea than me

 

[GaryE]

I'm thinking an infected or irritated wound. All the treatments used so far will have added to the irritation - and I'm going to suggest a weird one. I would get some betadine, a topical iodine based liquid used for humans. I would do a 50% water change. Then I'd net the fish and being careful to avoid the eyes and gills, put a little of the liquid (it stains everything - beware) on the affected area. Then dump our friend back in. Repeat daily, with the water changes, for a few days.
Then see what happens. If it is just a wound, it should heal. If it's something more nefarious (and Cory body armour can hide things, unfortunately), then the issue of what treatments you can get in your country raises its head.
Keep up with weekly 30% water changes if she recovers, and on the two of you go.

 

[Never too many fish]

Thank you! I have 4 other corys with the same thing and most have it on both sides. She is the biggest and very chunky, the 2 that dont have it are much smaller males. Should i do the iodine on all 5?