Hi Johan:
Gasflames and silvertips can easily throw one off when it comes to ID, especially when they look like the one in your pic. Silvertips are set apart by having, apart from their colouration, part of the digestive tract in their cerata, which this animal seemingly has as well. Now I battled with that, because I see it now and then as well, with animals which are otherwise clearly gasflames... so, what's going on? Well, it seems to me that most gasflames have opaque cerata and hence you cannot see it most of the time, but
some juveniles are more see-through, and hence you can see something.

Still doesn't quite solve it, but I do think this is a gasflame because the colour is just not quite right for silvertips, especially that coloured body,but also because of that funny thing between the rhinophores - a raised, curved section with corrugations. Image 6657 shows it well. Now, the silvertip has a much taller one, half a wheel, more or less, while in gasflames it is
flatter and in larger specimens virtually non-existent.

So, this is a gasflame.
Regards,

Guido

Nudibranchs of the Cape Peninsula and False Bay