Danios dying

[Tempestuousfury]

I posted this question before, but didn't get much help. Since then, three of my danios have died and others show the same symptoms.

Symptoms:
Emaciation of the "white part" that extends down the bottom of the fish. The fish look like upside-down arcs. I'm afraid the cause might be parasites because they seem to be eating fine.

I've also got 2 danios that are bulging. They may be laden with eggs, but there's also the chance that they have internal parasites as well.

 

[handsomeboy]

salt bath might help

 

[Tempestuousfury]

That would be far too difficult to do with eight of them. I can't add any salt either, because of the plec.