My girlfirend noticed that one had a cloudy eye. That one that two days later. The other one seems to be doing well. He is in a tank with 8 Panda Corydora's (3 adults and 5 children... home bred

1. Is it safe to keep my Cory's and Ocillefer in the same tank? I can set-up another tank for the Ocillefer if he turns out to be a aggressive fish. I don't see the Oci attacking the Cory's or anything, but the Cory's seemed to have been more comfortable without the small Oci in the tank. I think the Oci might be a bit territorial.
2. I gather it is best to only have one Ocillefer in a tank. Is this correct.
3. Was thinking of adding more catfish to my collection, maybe a Vermiculated Catfish and Upside Down Catfish (Nigrigventis). Assuming I set up two tanks, how should I divide up the following fish among the two tanks:
Panda Corydora's - have 8 but thinking of getting 4 more
Bronze Corydora's - have 2, and might ad 4 more
Otto's - thinking of getting a small shoal of 4-6 fish
Ocillefer - have one... can add more if he prefers a shoal, but I gather this is not the case
Vermiculated Catfish - will only get this if he is compatilble with the fish in either tank
Upside down Catfish (Nigrigventis)- will only buy if compatible.