I have understood that some fish "medicines" can still contain formaldehyde. I thought it not was in use any longer. Besides effects on humans (supposed cancerogenic and other effects) it can convert to a very toxic substance paraformaldehyde with time, especially toxic for fish. It is not question if – the question is when? Old batches can have formed paraformaldehyde and if it have been stored below 5 degree C - even fresh formalin can convert to the toxic form.
However – there is a chance to see this. Good formaldehyde is a clear liquid without any cloudiness – if you can see precipitation in one or another way – paraformaldehyde has been formed. If the bottle contain formaldehyde and show precipitation DO NOT USE IT
More reading here
Sincerely Lasse
However – there is a chance to see this. Good formaldehyde is a clear liquid without any cloudiness – if you can see precipitation in one or another way – paraformaldehyde has been formed. If the bottle contain formaldehyde and show precipitation DO NOT USE IT
More reading here
Sincerely Lasse