Oohitsae
Aquarium Advice Addict
Whilst waiting for sponge filter help replies, I am also curious...
What would come of an HM Plakat female and a VT male?
All VT fry, maybe with a little thicker set of body than the average VT depending in the lineage of the PK.
VT is the most dominant tail type out there and regaurdless of why you breed to it, you'll end up with CT's with messy finnage whic is why people so commonly recommend against mixing tail types.
Also long fins are always more dominant than short. Say you wanted to get CTPK, you'd have to breed the CT to the PK in the first generation, you'd get all CT's the 2nd generation, but they'd have the PK geno. Breed a fry from that spawn back to the parent PK and your F2 would be about 1/2 and 1/2 ct with PK geno and some CTPK. Then do an F3 back to the original, grandmother/father PK and you should end up with all CTPK in that spawn.
It's much easier to stay with the known tail types and not mix than it is to mix. Generally unless you have time to work 3 generations of line breeding, you'll end up with messy finned fish.
Oh and what was the sponge filter question?