I like Neons better than Cardinals although this maybe not popular opnionbut I do. And I never had trouble keeping Neons. As a matter fact, I got some second generation last month and they are about month old with little blue neon line. The red is not quite developed yet. Anyway, I believe both fish can be fragile. It all depends on the quality and timing of the purchase.
Yes, it is true that Neons have been bred in some Asia or Florida in quantity and not quality as well as some inbred and selective breeding which weakened the Neons. But I also know that most of the Cardinals are wild caught hence they can be weakened by the long trip and poor maintenance. They can be kept with minimum feeding and water change if that while they are waiting to be shipped. I said most because I hear some of them are start to farm bred in last year or 2. Also you can never know about the life expectancy of the wild caught since you never know the true age of the fish.
Anyway, so whichever is your choice. You should try to locate the quality healthy fish from reliable source. If you live in the big city town, one option would be try the local aquarium society. They sometime have auction or trade or such. And some of the member may have bred and raised and may have some extra fish to pass it on. And they should be healthier equal hardier since they do care about fish than people handle fish for business. Not to mention, they are most likely acclimate to your local water. Also less traveled.
I am planning to bring my home bred Neons to the Aquarium society meeting and auction if I get extra from most recent batch and next batch in month or 2. Although it might be not many extra that I love to keep as many as possible for myself that they are beautiful fish.
If you gonna purchase the fish from the store, it would help to ask few questions before buy them. Beside the typical question like the water parameter(temp, ph, gh) they are kept. You should ask where they are from, how long they are in the store. This could be important because it tells how far they came and how long they had to recover from the trip. Ovbiously longer they are in the store is better since it gives them time to recover and adjust the local water as well as time to medicate if there are some illness or dieseace. Sometime, it is tough to buy the fish that in the store for more than week since most store have stock day a week, some may even have twice a week they get new fish. So sometime it better to find the small store that have few customer. Although it is not always the case since they may not have many customer because their fish quality or service or price is not good. I guess you just have to look around and ask many questions.
Of course, you don't want to buy the fish from the same tank you see the dead or sick fish in it. Or some sickly skinny or deformed neither. If the store is reputable, they would not sell the fish from the tank like that. They would put the NS (no sale) sign and treat with proper medication.
So don't buy the first fish you see if the fish is not healthy. You can always come back again or check other store. It may take more time but it definately reduce the casuality and bad experience. And it may cost you more that you have to buy it again.
Good luck locate the nice healthy fish.
