Platy Help!

[gboi]

HI 
 
I am quite new to the tropical tank world. Ive had my 60l tank set up about 4 months now and its cycled and ammonia and nitrites are 0. I started with - 
 
2 x blue platys
 
when i got them home i realised they were male and female
 
After a week or so they became very quite hiding under rocks etc then white marks appeared on their tail. The LFS have me protozin which worked. they both perked up very happy all sorted.
 
Then after a few more weeks i bought the following 
 
1x female platy
2x male guppy
2x bentosi Tetra
 
everything was fine for a few weeks. but my 2 original blue platys keep getting this mysterious white marks on tail. it looks more like a smudge about 1-2mm one has a few dots on tail one has 2 marks. nothing anywhere else.
 
I have treated for 2 weeks with ESHA2000 and Esha EXIT to try and clear whatever it it. but doesn't seem to be working. any ideas?? i was tempted to to a water change add carbon then try protozin again. 
 
thanks
 
 

 

[Byron]

I won't guess as to the cause, except to say it has the sounds of fungal or bacterial, but I would advise to not keep adding medications until you have a fair idea of the actual issue.  On this, a photo may help someone ID it.
 
Medications affect fish, negatively, and always.  So any that are used will have detrimental impact on the fish, and if they are not going to cure the problem, this is far worse.  To ID fish issues is the most difficult aspect of this hobby, but something one cannot guess at.
 
On a related matter, you are adding too many fish for a 60 litre tank.  Three platy would be max, but female and male platy together will mean dozens of fry leading to hundreds; they won't all get eaten.  And Bentosi Tetra are shoaling fish that require a group of six or more, but that means more space as they get too large for a 60 litre.  Kept in smaller numbers can cause problems as they will react to the stress of this by becoming aggressive, or lethargic sometimes, and not live a normal healthy life.
 
Byron.