What disease could this be?

[JuiceBox52]

Melafix or something

metronidazole

 

[itiwhetu]

metronidazole

Yep

 

[Colin_T]

metronidazole is used to treat internal protozoan infections in fish. I doubt it would have any effect on a swollen head.

any idea if he has had other babies from the same parents, and if they were normal?

 

[JuiceBox52]

metronidazole is used to treat internal protozoan infections in fish. I doubt it would have any effect on a swollen head.

any idea if he has had other babies from the same parents, and if they were normal?

Not sure

 

[Colin_T]

I can't really offer any more help due to lack of information.

The only thing I have seen on fish like that is a cyst or blood blister type infection that occurs rarely, neither of which were treatable and the fish ended up dying. The fact so many baby fish have it, and they appear to be shorter than normal and looking somewhat deformed, would suggest a genetic issue from inbreeding.

Maybe try to find a specialist oranda goldfish breeder and see if they know what it is

 

[JuiceBox52]

I don't know the person, just saw the video and was like huh I dunno what this is