Beef heart buddy, keep the nitrates under 20 ppm and pump him full of beef heart, you'll see huge growth rates.
I used to get discus to bulk up from 2"-6" in just under 4 months using a beef heart mix:
5 parts beef heart, 5 parts raw krill, 1 part high quality flake food - blend it all together, ball it up in suran wrap, place the balls in the freezer and remove em' one by one as needed. =)