Anybody know what's the deal with pond-friendly fertilizer tabs?

I received my hybrid water lilies today, remarkably the same day that my back issue of pond boss magazine arrived. the july/aug 2010 issue, which has a great article on planting hardy water lilies. good timing!

I am going to plant the rhizomes in 2 gallon pots, with fertile clay soil. Using fertilizer tabs is also recommended. I was going to just drop by the farm supply store tomorrow and get some standard fertilizer tabs, like you would use with orchard trees. But then I read that the tabs need to be aquatic fertilizer tabs and fish-safe.

Should I not use the standard fertilier tabs from the farm store?
Any recs on specific fertilizer tabs that would be good for my lilies and safe for my trout?

Thanks for all your help, I promise pics will be coming when the little lilles make it to the surface.