ok so my only issue is possibly over stocking the 125g the stock would be two oscar a Jack dempsey common plec and the black spot but if I ran three canisters
a rena a eheim and a fx6 or fx5 and did 50% wc weekly more or less accordingly would it be fine?
No, fin level water changes twice a week to reduce nitrates to below 20ppm. Get used to that level of what change even if they are not 8-10" yet. Make it a habit.