Currently I just keep them. In the future, I may want to start breeding them or, possibly, showing them. For all I know I will be breeding them soon, I'm unsure of the gender of my pearlscale (my telescope if female). It's quite hard to tell with goldfish.
Though if I did start breeding goldfish I'd get myself some more quality specimens, the two I have right now are pet store fish (all I can get up here).