@Capn Tucker
You're right in that the only known images of a cat with a Knight's Cross are of U-48.
The design of the cat differs to that of U-564 though.
Apart from that ULAD clearly states in their decalset that the cat with the Knight's Cross belongs to U-564, although they don't provide evidence of this. So wether this is correct is another matter.
On the other hand, of you'd display a model of U-564 on a modelling event with a cat with Knight's Cross, I hardly doubt that anyone would ever notice (except if it's a visitor of this site
). So maybe we can make a deal to keep our mouths shut when we spot Roel's model...
Purely speculating now:
The first commander of U-564 was Reinhard Suhren who was awarded the Knight's Cross on November 3 in 1940.
So it might very well be that he took the emblem of the cat with him when he switched from U-48 to U-564 (in 1941).
And it might very well be that this cat sported a Knight's Cross mirroring his "master's" Knight's Cross. But that is purely speculating, as there is, to my knowledge, no photographic evidence.
The picture shown in cola's post is apparently from the 7th patrol. By the 7th patrol Hans Fiedler was the commander of U-564, who was never awarded the Knight's Cross.
So it might be that the cross was removed after Hans Fiedler took over from Reinhard Suhren.
In that case it might very well not be so wrong to depict U-564 with the cat with Knight's Cross. At least not until someone finds a picture to proof otherwise...