Barb

[the redrover]

Any one help please, have spent time searching but have not found the answer
I have some gold barbs generally very happy and playfull but have lost three - one at a time seperated by a couple of weeks
The symptons always the same - Swim near the top, lower belly bloated and overall colour changed fron usual gold with red fins and nose to a light pink. Nothing else obvious, no spots blotches etc.
Water is maintained and checked, carbon filter regularly changed and when water is partially changed it is treated first. Other fish in tank have been there all the time the barbs have and are fine. (six guppies and a big soft catfish)
Thanks for looking

 

[saltynay]

Internal parasites perhaps. What does their poop look like?

 

[lordofthesea]

are their scales sticking out like a pinecone?