Nitrite 11 PPM??? Yeah, that'll do it.
It's fairly obvious the tank wasn't cycled. I suggest hopping down to the Freshwater Newbie Forum and checking out a great thread near the top called: Sticky: Cycle. It explains the process by which aquaria gain nitrifying bacteria in order to sustain fish by eliminating their waste, otherwise known as cycling. It's a very good read and after you understand that, you'll find fishkeeping becomes quite a bit easier.
It's fairly obvious the tank wasn't cycled. I suggest hopping down to the Freshwater Newbie Forum and checking out a great thread near the top called: Sticky: Cycle. It explains the process by which aquaria gain nitrifying bacteria in order to sustain fish by eliminating their waste, otherwise known as cycling. It's a very good read and after you understand that, you'll find fishkeeping becomes quite a bit easier.