Yes sounds good to me you have
over and under and mid level filtration. You want to know if the tank
is adiquit size. I have 2 answers.
First,If the fish were at full maturaty no the tank may not be the right
size and the red devil would most likly pounce the oscers and kill.
Second,If the fish are 2-3-4inches when you bye them you culd
have"exmple"3 red devils 4 oscers 2 green terrer 3 pleco 2 cat fish
and maby somthing elts. butt as the fish get bigger you will need
to sell the ones you dont like as mutch back to the fish store.
Some people dont like to do it this way but remembe fish are a
hobby not pets.red devils are pry faster growing than oscers and
more violent lots more. Vacuming gravil and 20% water changes and
adding cycle and start right are most important yo a helthy aquarium.
I do mine every week.
MY TANK 100gal
1,fresh water baracuda
3,vampire tetra
1,bolvirian snub nose
1,sting ray
1,tire track eel
1,needl nose gar
2,bristil nose pleco
1, cat fish i do not know what the hay it is but its cool.