New tank... did we add fish too fast? One not eating?

Question
Hello there, and thanks for taking the time to answer all these questions.  :-)  
My daughter received a 10 gallon hex tank for her birthday.  The guy at the
store seemed very knowledgeable and said we could add the fish after about
24 hours if we treated the water with conditioner, let it run through the filter
and come to room temp, and then added some sort of "instant bacteria" stuff
and then the fish. They also gave us some extra tank water from their setup.
(We did ask for the quickest way as she is 10 and of course wanted the fish
ASAP.) The tank contains well rinsed colored aquarium gravel, 3 plastic
plants, and a ceramic shark meant for aquatic use.  We added two glofish and
I think the other guy is a gold barb.  This was yesterday evening, and so far
they seem fine and active, although I noticed when we fed them this evening
the barb did not eat anything at all.  He does not act sick in any other way.

I guess all this is to ask if we completely jumped the gun by adding fish, and
what are the steps we need to take to make sure the "cycling" process is
completed correctly without killing them off?  Also should I be worried about
the barb not eating, or do they sometimes do that?  He has always eaten the
few other times we've put food in so far.

Thanks again!

Answer
Hello Melissa:  New tanks can be tricky... I would take a sample of the water to the place where you bought the fish and ask them to test it for you... usually this is a free service.  It is also an important step in diagnosing tank issues.  If the water chemistry is good... then the cycling process may be over...  If the water chemistry is out of the normal range then I would do a water change of about 2 gallons and add a double dose of beneficial bacteria to the tank.  Barbs are usually greedy little fish with huge appetites... their desire to eat reminds me of a shark frenzy which is one of the reasons I love barbs.  If he does not eat today... then I would try to feed him some brine shrimp... frozen would be fine.  If he does not eat the brine shrimp then I would consider medicating him with aquarium salt.  IF he shows no sign of improvement by Wednesday then I would medicate with General Cure as a precaution.  Did your tank come with a heater???? If so what is the temperature????    dave