Tank size depends on the species largeer species need larger tanks
Occelaris are said to be and easy fish to breed, they should need 10 to 20 gallons
Youll need some hard substrate for the eggs to be laid on
Any type of filtration should do...i did a fuge on mine, just to keep my options open
Lighting should be 12-14 hours per day but you dont need an expensive set up
Any sort of heater will do so long as it can keep you aroun 78F- 80F
I strongly recommend Joyce wilersons book Clownfishes it has an entire section devoted to setting up a tank specifically for clownfish breeding and, The sections are short and to the point