In the pilot, only five are ever seen on screen at once. But, as noted by repcisg over in
http://www.colonialfleets.com/forums...5&pagenumber=1 , the formations show suggest more ships off camera, and that the 5 on screen are not always the same 5.
In the pilot, dialogue mentions the Atlantia (shown to be a battlestar), the Galactica (obviously a battlestar), the "Battlestars Triton and Pacifica", and the "Battlestar Acropolis".
Production notes also name the Solaria as destroyed at the Peace Conference, and some notes suggest that Pacifica was destroyed before the Conference (which conflicts with dialogue).
The Pegasus was presumed destroyed before the the Conference, but turned up intact in Living Legend.
The Columbia was where a prisoner being interrogated by the Cylons claimed to be from, but he was clearly lying. The Cylon said the Columbia was destroyed at the Peace Conferenc, but may have been lying or mistaken.
The Rycon (or Reichon or whatever) was mentioned in Take the Celestra as the Battlestar that Commander Kronus (Commander of the Celestra) used to command. It may have been destoryed decades ago, as he is older than Adama and retired.
Other names here come from production notes, novels, comics, and such.