We have had Bolivians for nearly four years, same wild cought, some captive bred and both have had wigglers (till tetras find them...). Tap water EC 450-530uS (tank has been 850uS sometimes, nowadays with RO 300-350uS), GH 3-5, KH 2-4, so I personally cant call them sensitive. Originally we had 9, but have lost two because of Camallanus infection, luckily the rest made it fine. One didint grow well and was culled later. Thou, we have never tried to grow fry in separated tank so no idea how succesful or not that would be in our nasty water.