Originally Posted by AFishTale
If I bred the last male with a HM female, is there a possibility that the offspring would have fuller fins? Or is a DT x HM not a good cross?
If the female is from a true HM line, and is a good HM specimen- yes, you would get a few HM offspring.
Speaking of "good or bad" crosses depends on your goals. If you want to create show quality fins in only 1 or 2 generations, then yes it's a bad idea.
dT x HM crosses will need a high percentage of surviving fry to then be selected for the following generation and so on. It will take you at least 3 generations to get HM that will breed true - unless of course they were from a HM line to begin with.
IMO your copper may be a HM, so you should get HM offspring .... can you get a side view picture of them flaring.
If you want to be 100% sure, get a female with a 180* spread, with 11 base and 4 end ray branching and preferably with pointed tail edges.