My 3" jar is very picky. So far it will only eat bloodworms and occasional crickets. Would gut loaded crickets + bloodworms be an ok diet until he's big enough to starve on to pellets? Should I keep removing the back legs of the crickets or is it unnecessary? I heard they were sharp and could harm baby aro's
You could introduce dither fish to increase the competition so the arowana is more willing to feed on the pellets rather than starving him which shouldn't be done at this fragile stage.
Try a few Tiger Barbs for tankmates. They're quick enough and will eat anything. Your jar just needs to associate more things as food. My jar is now about 4-5" and has eaten shrimp, bloodworms, pellets, tiny frogs and even flakes since I brought it home a couple of months ago. Good luck.
Just had a look at your sig, my jar and its Tiger tankmates are in a 70gallon though.