Sigh. gamer's right. I'm beginning to hate my LFS. All of them.
Danios should be given at least 20 inches of length to swim in. Mine currently have 12. My larger tank that I've just aquired has 3ft of length (it's huge), but I have no filter/sump/light/heater/tank stand etc etc for it yet, all of which is really expensive when you buy what you're told is best for your fish.
All of my danios are schooling nicely, none are hiding, none are biting. Yet. I'm guessing it's just a matter of time until I get social problems and one goes off and hides, and they start dropping off one by one.
Any advice?
My advice is to stop stressing. Danios don't know they need 20 inches of swimming space. In fact, if we want to get real anal about it they shouldn't even be in captivity right? They have not read the books. And these claims of 20 inches are arbitrary numbers decided by someone that become gospel because someone else reads it and believes it. No one asked a danio how much room they needed.
The point is, yes, they need as much swimming room as one can give them. And they would be the better off for it in the long term if they had more swimming room. But right now yours don't. SO what you need to concentrate on is providing good water quality and a decent diet for yours until the new tank is set up.
People have been breeding zebra danios for decades and raising whole broods in 10-15-20 gallon tanks. I have raised hundreds in 15 gallon tanks before I started using ponds. So your few that you have are not going to complain over the 5 gallon tank you house them temporarily in.
One problem you might encounter is the fact that most commercially available fish these days are crap. They are bred in asia with no regard for genetic quality and health. It is a numbers game and the name of the game is money, and how much you can make.
Danios are one of those fish that decades ago were impossible to kill. Nowadays you visit stores and if you look carefully into danio tanks you see hollow bellied, skinny, bent spined fish swimming around with what appear to be healthy fish. But because of deteriorating quality of broodstock very often the fish we buy that appear healthy end up becoming skinny sick fish as well, and then aquarists are led to believe that it is because of something they did wrong. And then they buy meds and expensive bottles of this and that to fix something that cannot be fixed.
And then there are danios like your, "Longfin Metallic Silver/Pink/Ghost Danios". What the **** are those? They're not in any book. They are, I'm guessing, a longfinned glo-fish type fish. Most of these are crap as far as quality is concerned and will peter out on you sooner or later.
My point with this rant has been, stop stressing, provide good water quality, feed a quality diet sparingly and your fish will have a good chance of making it to your large aquarium when you get it set up. My point continues that if you do start seeing fish falling apart as it were, it is very unlikely that it is because of anything you are doing, it is because the fish were crap.
Crap like most fish imported in these days.
Bill