I've had my Cren. Multispinosa with mellow South Americans in a slightly lower PH since I've had them and up until this point all was going well until last night. I noticed my Pike starting to go after some of the mellower tankmates and I must admit some of them were smaller than they should be but up to this point the Pike has shown no interest in them. Well I think i should move the Pike into another tank and I have a 150 with some Argentea, Robersoni and a few Black silver dollars which are all small at around 3.5 to 4.5 inches and of course more aggressive than their South American counterparts. I quess I'm wondering if the Pike would (A) be ok with the Argentea and (B) will the slight difference in PH cause problems? The PH in the South American tank is at around 6.9 while the PH in the Central American tank is at around 7.4. It would be easier for me to move the Pike as opposed to moving all the South Americans.