One Of My Fish Has Died And Worried About The Rest - Total Newbie And

[cuttlefishspike]

Hi - Ive had a troipcal biube for just over two months now. I have 8 fish in it and they all seemed just fine but I woke up this morning to find that one had died. I bought a PH testing thing thing and it looks like it is reading 9.0 which according to the guide is way too high. How do I get the level down - I'm so worried about the rest of the fish.

Please help.

 

[OohFeeshy]

How bigs the Biube, what fish, and, um.... Got any rocks in it? Or shells?

EDIT- And what test kit are you using, and how long ago did you get it?