sick fish????

Question
Karen we just got a 10 gallon aquarium set up, we put it up bought fish put them in, they were fine bought them 3 days ago. the fish we purchased were 2-guppy fancy assorted, 2-ftetra serpae large, 2-ftetra black neon, 1-seachem prime, 2-swordtail pineapple, 2-ftetra rasbora het, 2-ftetra neon x-large. One of the little fish orange tail keeps staying right at the top of the tank, she has been doing this for a day and a half now, Now one of the other fish is staying up there with her comes down every now and then. Could you please tell me what possibly could be wrong. Also do we have too many fish in the tank. We have an undergravel filter with a bubble tube on each side, bubbles are coming from both sides.  Thank You for you help Karen.  Cindy

Answer
Hi Cindy,
The biggest concern is the tank being newly setup, it lacks a sufficiently established biofilter AKA the beneficial bacteria. All aquariums must establish a biofilter, this is because when fish produce ammonia from their waste.. the bacteria must be established well-enough to control it and convert it first over to 'nitrite' and then finally into 'nitrate' which is harmless. The bacteria take about 4-6 weeks to establish sufficiently. You can test for all three levels and monitor how far along your tank is in establishing the biofilter.

You must be careful when first adding fish to your aquarium. You can encounter problems if you add too many at once, overwhelming the poorly established biofilter and causing ammonia spikes (ammonia being very dangerous to fish).

The best thing to do is try to get test kits for ammonia, nitrite and nitrate. Monitor them at least everyday.

At this moment, I'd do a 50% water change to reduce pollution. Make sure the new water is treated with a water conditioner and the temperature is equal to or just a bit warmer than your tank.

If you notice your fish are stressed the best thing to do always is a 50% water change. It helps fish get through the stressful time of cycling and there is no better remedy.

I do hope this helps!
Karen~