I have an FX5 and a cerges reactor on a separate loop in there that moves/cleans a lot of water per hour. I actually rehomed 8 cherry barbs and 6 harlequin rasboras last night in anticipation of moving these guys in. The Bolivians seem very healthy at the moment, but I do agree that things could get fun once they come into breeding season. I will certainly keep my eye on that.
I had hella time with Bolivians that my LFS was getting. I eventually gave up and out of the original 6 I bought, only one is still with us 1.5 yrs later. This new batch came from a guy off Aquabid and they are little beasties healthwise. I am quite happy with them.