My tap water pH is 8.0 and I have tons of otos (just put 24 in my 75g tank, lost just 1). I also have about 75 cardinal tetras between all my tanks (maybe 100, it's too many to count). They do great in my high pH water.
This is true for almost all fish. There are a few out there that truly require that the water be altered, but they are very few. If in doubt, you can always ask. I think most people have higher pH tap water.
Vicki —Rena Filstar pimp #142 (four XP4s/three XP2s/one XP1) • Eheim pimp #301 (Pro II 2128) • Victor pimp #27 (VTS-253B-320)
• 90g - Journal
Pelvicachromis taeniatus 'Moliwe' ——
• 75g - Journal
Pelvicachromis pulcher 'Lagos Red' Better Pics 8-24
• 29g - Journal
Pelvicachromis pulcher 'unknown' —--
• 29g - Pelvicachromis taeniatus 'Moliwe'
• 5g - RCS colony ——————————————————
• 2.5g - Journal