a gar will outgrow a 110.. I've fed my Oscars live for years.. minnows are fine.. goldfish are not... as someone else already said.. I do it as enrichment.. gives them something to do to keep them from developing some bad habits. And Mollies home-grown would be fine as well.. my guys also love nightcrawlers, and have packed on some nice weight and color w/ a variety of live and pelleted foods. ATM I have a sun cat/eclipse cat as they are often called.. get approx 12" but usually less. they look similar to a bullhead imo.. but have a more chocolate color to them and some yellow. not a very colorful fish, and I rarely see him, but my tanks extra food vanishes. And I've never had conflicts between him and my O's. They are also cheap, and readily available fish, and hearty as anything else I've kept. commons plecos... beware. slime coat suckers potentially, and will grow huge, and are far more dirty then most others.. but by adding something to eat extra food.. you are swapping one problem for another potentially.. food bits to suck up/ more poop to suck up. nothing is going to eat the extras.. and produce no waste... But if there is.. I'de like 8 plz!
for any other tank-mates your best off imo w/ other Cichlids. Oscars usually are all talk.. no show. Playground bullies. I've found fish that are inconsiquential to teh Oscars shows.. but can take a hit or two and not rip them up make the best tank-mates. and tbh.. one of the best co-mates I've had for an Oscar.. Is a koi... lol.