I have two synodontis petricola that have lived toghether in various tanks for about 2 years, right now they are in a planted 55 with lots of hiding places with some cl's(7-1") some plecos and some small gobies. can I add maybe 2 or 3 more pertiolas safely? they haves ones at the lfs are way smaller($20) and some that are just slightly smaller for $40 i think.. would either be ok? would they breed? thanks