NovaCracker
(And to address 'unpopular' breeds.... Speaking only as my opinion I find them mildly interesting and not must-haves because of either breeding restrictions (Mers) or the fact I can't do a male betta-tail type without it being a mutation. That's me.).
Actually, it's not a mutation to get that: In fact as we update the Mers, the 'Mer-Kelpi" hybrids will be getting an UNEDITED "Fancy" fin style which IS based on the Betta. As well as the Eel, Fierce, original, deep sea spiny, shark and orca for the Mer-Kelpi hybrids. Not to mention Pure Mer fins variations (that Kelpi-based Mer Kelpi hybrids will eventually have available as well). 83