filter is a Eheim 2212 internal with no fish bits found.
i had a really good bout with the first group of neons, added 6 and 6 survived for 8 months. the pop eye which popped claimed one and another got its head stuck in the motor prop of a pump (no longer in tank (both fish and pump)) and as I only had 4 left, decided to up the group to 10. but the local store had 10 for £5, thought what the hay. 1 died on t'way home another died in... well stress from rehoming really. I now seem to be down to 5 or 6 young ones (a bit difficult to count when there is as many.)
the plec eating the remains would make sense, it does happen in the dark at night....