I had an established mixed com till a few weeks ago. Then I added a small 4" endli and on the second night it ate one of my rummynose tetras. 5 days later it ate another. I knew I'd have to move them fairly soon but wasn't expecting to have to do it quite as quick as this. Needless to say the remainder - including my other smaller fish (incl sidthimunki botias) have all been moved now.
I once bought a pair of golden algae eaters and put them in e same tank as my ornate. That was around 2 in e afternoon. At 6pm I went and checked and both GAEs were gone =P