more fishes......???

[ima_kitty_kat]

I have a 20 gallon tank with a rainbow shark, 1 male and 1 female paradise fish, but its looking pretty bare.
I have a few plants in there, but nothing that couldn't be replaced.
Would it be possible to put a couple of the smaller, say maybe 3 in., cichlids in there?

 

[ima_kitty_kat]

ooops, forgot lol

O, oops..forgot some fishies...=P

i also have 4, hmm, maybe 2 inch long killifish in there, but the bigger, more aggressive fishes seem to be leaving them alone.
if i must, they could be separated too....or taken back to my peaceful 10 gallon tank.