I currently have 2 peppered corys in my 20 gallon tank (along with 2 female platys and 2 female swordtails). I would like to get a couple more corys, as i know they do better in groups of 4 or more & and they do well at cleaning up excess food when i overfeed , but would also like a little variety in the species. do all corys do well together, or should i keep it to the same species ?