swelling

hi i have button polyps, brain coral and brown star polyps in a 10l (3g) nano aquarium with nothing other than a serpent sea star. the tank has bee running for five weeks and up until yesterday everything was fine with my button polyps but some (about 5 of 25) have suddenly started to swell like...

I went to feed my snowflake eel today when I noticed that one of the feeders had this hideous, swollen tail, almost like an enormous bubble had formed between the flesh and the scales. I looked into freshwater diseases and could find nothing similar. What I want to know is if I can still put...