The most profitable would be some of the rarer, basically unavailable species, Crenicichla sp. Bolivia 'Citrus', Crenicichla sp. Inirida III(I believe this is the dwarf one), and basically ANY of the Teleocichla sp. Of the actually available pikes, Crenicichla notophthalmus, Crenicichla sp. Orinoco 'Dwarf' and Crenicichla regani are probably the most profitable. True notophthalmus can he hard to find though. One thing to remember, even the dwarfs aren't real dwarfs, many still reach 7 inches.