Flame Gourami died - no signs of illness/injury

Question
Hi, I've got a 25gallon setup..had 6 dwarf gouramis - 2 gold, 2 neon blue and now 1 flame.  They are new to the tank... 7 days today. All seemed fine, got their beautiful colors (they were pale in the store - told it was due to stress) so I thought everyone was happy. Last night, I fed my fish, they all ate like pigs.. then an hour later, one of my flames was floating straight up and down with his nose in the air - not at the top - around the center of the tank. I thought he was dead, then he jolted, swam a few seconds and froze again.. Less than 30 minutes later, he was dead???  No obvious signs of injury or illness?? He was full grown when we got him.. was he possibly just old?? Do fish die like this for no obvious reason? I've had fish die before, but usually from obvious disease, never like this. What precautions should I take with the rest of my tank? Water tests all ok. Thank you.

Answer
Hi Janet
Sorry for fishie loss!  

It's possible he was just old, it really could've been anything.  And yes they can die like that with no symptoms showing.  It's hard to diagnose sometimes even when there are symptoms present, because so many diseases, parasites, poisonings have the same symptoms, makes it hard to narrow it down sometimes.  And it's not good to just go dumping a bunch of different meds in the tank, that's pretty stressful for the fish as well.

Make sure your ammonia and nitrites are showing 0 ppm, and nitrates under 20 ppm.  Those are really the only acceptable levels, some test kits will show a little bit of ammonia or nitrites is safe, but it's just not the case.  

When buying fish, granted pet stores usually aren't the best condition for a fish, they're overcrowded and such.  But that's temporary because they're generally selling the fish.  Make sure the fish you buy are healthy, look & act healthy, swimming around, you can ask the employee to feed the fish a little bit as well, no white spots, or fungus, etc.  Make sure there's no dead fish in the tank(a good store will remove them frequently).  One or two here and there is normal considering, but if you see a bunch of dead fish in all the tanks-don't buy from them.  Also, most stores have 1 big filtration system running all the tanks, so if one tank has a problem in it, most likely all of them have the potential to have sick fish.  So make sure all the fish appear healthy.

Keep an eye on the rest of the fish, look for obvious signs of lethargy, not eating, not "hanging out" with the others, rapid breathing, scratching/rubbing on objects in the tank, darting around, gasping at the surface.  

Good luck with the rest of them!  If you have more questions, please ask!

Christy