All 4 fry have ventrals. I think they were so small I couldn't see them.
LBF: I fed them the night before the power cut but I think you could be right as I noticed them swimming better when the water was warm. They do dart around now but when they rest at the bottom they lie on one side... maybe cos they're bloated? They have really round bellies..
If looking at them from above the stomach area is really round but the main body and tail is really thin... The proportions look odd. From the side they look normal I guess. I'll see if I can get some photos of them..
Is it worth fasting them and adding some Epsom salt at this young age?