Join Date: Oct 2010
Location: Victoria, Australia
Hardy fish to me are things such as goldfish and bettas that can survive through the inevitable mistakes beginners are going to make. Look how many goldfish and bettas survive in airless, filthy bowls around the world. These fish can live in abhorrent conditions for years before finally succumbing.
I doubt a CPD could even live a week in such poor water conditions.
I am not saying that the OP is going to do this to their fish, but I honestly think that CPD and other very small species of fish are not appropriate for someone just venturing into the hobby. Nothing is more off-putting than coming down one day and finding all your livestock dead. I've been there, done that and own the tee-shirt. It's why it took me so long to get back into fish again.
I think a hardy species of danio such as leopard, zebra or pearl is a much better option. Once the OP has a little more experience, then I would say that it may be a better time to select some more challenging species of fish.
Also my CPDs were definitely quite a shy fish, and I have heard plenty of similar stories from other owners on other forums. Unless the OP was willing to invest the money in purchasing a large amount, you are probably not going to see much of them in a 250/300L tank.