Siamese fighting fish lying on its side. Normal?

I just had an enquiry about whether it’s normal behaviour for their Siamese fighter to lie on their side when the water temperature drops over night.So, I pointed them to one of my previous blog posts – https://thefishvet.wordpress.com/2011/06/05/fighting-fish-over-wintering/
Another differential diagnosis is mycobacteriosis which is common and is a zoonotic disease, so watch out!