Sorry Greg....
The trick is getting them to reliably feed on anything but live foods. The next trick is buying a healthy one.
There is no trick involved with picking a healthy fish.
You want to watch the fish in the tank he's in. Is he swimming normally? Picking at food? Breathing relaxed? acting normally? etc.
Ask your dealer to put some food in the tank. (If they won't, maybe you need to find another dealer.) Does the fish eat? Does the fish try to eat? (Sometimes a fish will not like what it's being fed but tastes the food being offered. This is a good sign!)
Next, there should be muscle/meat behind the head and a full stomach. If the stomach is pinched, not a good sign.
If the fish is doing fine in the store but not in your tank, the problem most likely is not the fish. It's your tank. A healthy, eating fish will not just shut down for no reason. How you're keeping them is usually the problem.
Now, I know this may piss off the internet sellers but if you want a better guarantee of getting a healthy fish, GO PICK IT OUT YOURSELF and follow the guidelines I just laid out!!!! Yes, you WILL PAY MORE for this but how many dead fish you will buy sight unseen vs healthy fish you buy following my guide will offset the difference.
I've been very successful at raising tiny fish into full grown adults because I followed this same system. Sometimes you have to wait for the right fish. Be patient!!! If you reduce your risk, you raise your success. Buy a healthy fish from the start.
See, there's no trick to it.
