Sick lemon tetra

[..puSkar..]

Have you tested your water?

No

If I did not test my water...

1. ...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

41-50%

How frequently do you change your water?

Every week

If I do not change my water...

1. ...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

I've had this group of 5 lemon tetra for 7months now. They were completely fine but yesterday I saw this bulge on one of its fins. Did a lot of searching but didn'tt find anything about it . What do you guys think it is? Is it curable? Transferable? Dangerous to others?
They are in a 36*18*18 tank with a 2" Vieja. Weekly 50% wc. And temp at 28°c.
It was just a bulge yesterday but today something witish like a cotton fibre was coming out of it.

 

[..puSkar..]

Charney any suggestions?

 

[..puSkar..]

Rocksor what do you think it is?

 

[Kolton13]

kno4te knows more than me about. But i'll ask the basics. Does it look cauliflower like? kind of hard to see with the lighting. Is it bright white? What are your perimeters? Looks like a fungal disease but as I said Ron knows probably lol.

 

[..puSkar..]

It's just like a bean seed. It's on both sides. It's reddish brown. I don't know the parameters cauae test kits are very had to come by at my place. But to my knowledge they should be within range. Cause I never miss my maintenance routine.

 

[kno4te]

Hard to make out a bit but almost looks like something attached to the tail. Looks like anchor worm or something. I’d try and net the fish and take some close up pics. Get a pair of tweezers and see if there’s something to take off.

 

[FJB]

Can't quite make it out, but based on the first image, it looks like an external parasite, something like an Ergasilus (copepod).
If I am correct, It is usually not lethal or contagious, but needs to be removed from the fish, easiest is physically pulled out with fine forceps. I don't know how to attack it chemically, but I would say the same way as most external parasites. It is more commonly seen in larger fish, but I guess this is the first I see in a lemon tetra.
Again, although not contagious, it may be that a colony is established in your tank.
And then, I culd be totally wrong...has happened before. Good luck!