Acestrorhynchus

not an expert, but maybe just my experience will help.

1) I have large (8"+) most likley falcatus, possibly altus .
2) mine is a bit unusual in that he is in with relatively peacful cichlids (jurapari, severum), a dat, a 10" ATF, bichers, mbu... various other fish. Most people will tell you NOT to keep them with cichlids or anything that might possibly harrass them. I would agree. They can be fairly delicate when it comes to bullying. But mine has done well. He mixes it up on occasion with other fish who bully... but that is just weird. So recommendation is to keep them in a school (or shoal?) of at least 5 same0size individuals, and any other PEACEFUL fish that is too large to be eaten. Angelfish would work. bigger gouramis might. Maybe very peaceful cichlids like Jurapari. Bottom fish ok. Don't try to mix with an ATF or any boisterous cichlids or characins.
3) your blue gouramis: they should be fine as long as they are same size as the aces OR LARGER. If they are smaller, they will be eaten.
4) I feed mine ONLY frozen silversides (thawed).... hand fed every other day. WHole. Dangled in the water and he hits them HARD. I know of at least 2 other people who have gotten theres to eat pellets. Some people have no luck and can't get them off feeders.

Hope that helps a bit... best thing, get a school of them, in a species tank or with a few other large, peaceful, mellow non-predatory fish. They are not mean, a little fragile, but will eat anything they can fit in their mouth. They are more comfortable and relaxed in groups.

BTW, even though I have a larger ATF, a nice hungry pbass and other fish that "HIT" hard on the food, I still love that Ace... he is so damn fast and badass when he eats. Its great.

I hd 2, some of the best fish I have kept. They were irridescent gold that shined a blue/green hue.

THey are very fun to watch eat, the best, more fun than a vamp tetra or ATF.

They can chop a good sized goldfish in half no problem, if they did have a brawling mentality they'd be able to do some damage.

Mine actually got left alone by my pbass jardini and red snakehead.

I recommend them a lot, don't bank on them eating anything but live though. They would occasionally chomp some prawn dropped in front of a powerhead to simulate movement, but would spit it out.

The only ate live fish and river shrimp. Which cost me a fortune seeing as feeders are simply full priced fish in England. 3 dollars for 1 goldfish.

Very good advice given above! I have never tried to get them completely off live food but they did tkae the occasional pellet if I dropped it in at the same time as live crickets, They will also take small earthworms. If you drop food into the flow of the filter return they are more likely to take interest.