Okay, I'll repeat what I said last night.
You could POSSIBLY keep the acaras or the eels long term in that size tank, but NOT both, and either of them will cause havoc with the mollies, cory cats and danio. The eels, when they are a little bigger, will start eating anything they can fit in their mouths. Acaras are aggressive and territorial, and especially if they try to spawn, they will shred anything that gets in their way.
The oscar needs a tank that is double that size at the very least, and it needs to be kept alone, with other oscars, or with similarly-sized fish like other South American cichlids or plecos. It will eat most of the other fish in that tank and has already started causing you problems with its aggressive behavior. you can't blame a fish for acting naturally.
The bala sharks, clown loach and pleco are all peaceful fish, but they just get too large for that tank and will never be comfortable in it long term. You're condemning them to a life of misery trying to keep them in that tank. The sooner you move them, the more likely they will be happy, so you either need to get a bigger tank, or rehome them before they get so large that moving them will be extremely stressful.
The black ghost knife needs a much larger tank and is also a very senstive and hard to keep fish (two of them have already died in your care.) I'm assuming, since you have stocked a tank like that, that you are an inexperienced fishkeeper. BKGF are NOT beginner's fishes. They are too sensitive.
The krib, danio, mollies and corys are fine to keep in that tank long term. The krib is a semi-aggressive fish, but with only one he will cause very little disruption (The problem is when you have a breeding pair because they will aggressively defend their nest site and their fry.) You can have any small community fish that the krib won't eat (so anything larger than small tetras or guppies) but make sure you don't overcrowd the tank this time, because at the moment it is overstocked and the filter will not cope with this sort of fish load. Most of the fish you have in the tank are what we call 'tankbusters' - they are fish for specialist aquarists because they grow very large, produce a lot of waste for their body size, and are often aggressive and carnivorous in their feeding patterns. If you have a 250 gallon tank and you want to put tankbusters in it, you CANNOT stock it with 250 inches of fish - in fact, if you put five large cichlids, like oscars, in it, most people would agree that it was fully, if not overstocked. It would also need a very heavy amount of filtration. The filtration on the Rio 240 is designed to cope with the relatively small (in relation to body size) amount of waste produced by small, mainly schooling, freshwater fish. It cannot handle that many tankbusters.
Your entire tank is a ticking timebomb because it is overstocked, underfiltered, and crammed full of fish that are incompatible. Once they begin to reach sexual maturity, or get large enough to feel crowded, they are going to start ripping each other to shreds. You've already lost several fish. The faster you find new homes for the fish that HAVE TO GO, the less likely that you're going to kill more.
PLEASE take our advice... we don't want to wreck your tank and your plan for it, we can just see what's going to happen if you don't fix it, and it's not going to be pretty. We don't want to turn you off the hobby, but we know that what will happen if you leave a tank like that (utter chaos and a lot of fish deaths) will do it far more effectively than anything unintentionally discouraging we could say. If people are getting a bit snappy, it's because most of them have been telling you to rehome those fish for weeks.