You might have to remind me on the set up....This is mostly for @Wills: It turns out that the festivum will eat hemiodus gracillis; they dont' swallow them per sey they catch em and then disect em....
10ftx4ft - the largest fish currently are the festivums; there are some medium size clown loach (5-7 inch); and some angels. The festy are mixed size with I presume the females around 3 inch and largest male 5 or 6 inch. The female festy used to do this with serpae tetra; she would catch them in the middle and then rip them apart.You might have to remind me on the set up....
But surprised to hear they are actively biting them rather than swallowing small fish. I did once have 2 Festivums that were very aggressive but never knew which ones they were. Were the Hemiodus a good size?
Wills