Sounds like you have defective predators, LOL I wouldn't think the synos would eat the fish, neither the parrots nor the acaras or the severum...The only true predator you have is the Oscar, which sounds defective. Maybe get a redtail catfish or a gulper. OOOOH a gulper would take care of those pesky cichlids. I promise you that, but you may want to remove any fish you don't want eaten...
LOL they're in different tanks.
The synos are basically bite toys for the oscar (depends on mood). I moved them to different tanks but every time they were with hrps they got skin stripped like they fell in a bag of cats.
Of the parrots one has a mouth big enough but can't catch. The other two love chasing hrps and cornering them. Fights ensue. I really think the parrots just get involved for the fighting, not eating.
The acaras came closest on several occasions and had ambush tactics in addition to directional speed. I think they just had bad luck because of large tank size and too much cover/escape hides for the fry (they would scatter too). I absolutely believe they would have picked off quite a few under different circumstances.
Severum was fast enough in a straight line to catch but couldn't switch gears/direction enough.
Anyone who has an oscar knows they don't spend energy chasing snacks. Brick would snap at the half grown ones but soon got bored once it was clear he couldn't catch with speed. Can't catch anything with 90 degree turns.






