We had one that was about 8" or so long and he never bothered the other fish in our tank. Which included angels, gourami, pleco, and umm I'll have to get my hubby to put his

in because its been over 4 years since we had that tank. Depending on the type of cory's (unless they are dwarf) I don't think you'd have to worry too much about them the tetra's I'd worry though. My suggestion would be too keep a nice supply of ghost shrimp in your tank. The bgkf love them and ours was known to eat close to 2 dozen in one night.