Ok. So you went offline.
According to your profile, on the 10th March you say you were in the 1st week of fishless cycle. Unless you added mature filter media from another mature tank, there is no way your tank has cycled after 7-9 days. Which means that your Tiger barbs are being subjected to high Ammonia, to be followed by high nitrItes. Both of these are highly toxic to fish. If the guy at the LFS is "sound" and he said it was ok to put fish in before the cycle finished then he is not so sound i'm afraid. A fishless cycle can take anything from 6-12 weeks.
I'm not getting at you, as you may well have been going by what the guy at the lfs said to do, and you may be a first time tropical fish keeper. If this is the case, you really need to supply all the info so people can help you

Your barbs may well come through the ammonia & nitrite but it may well cause damage that shortens their life.
Did the lfs guy tell you about testing your water? Believe me, there are many many people that work in lfs' that may well sound knowledgable, but there's a lot that just want sales. I guess they think that by telling people they can put fish in now, means they get the sale, before you can have a look elsewhere.
People will try and help on this section regardless of what species of fish you have, as the basics of tank husbandry are the same
EDIT: Just seen that you have been given advice in the "New to the hobby" section in the thread "Seeding". You've added the Convicts then. The gravel you added will do nothing. As you state on that thread, you have had no show of ammonia, nitrIte since starting the tank. That means the filter hadn't even started cycling. That now means that that your Tigers, the Convicts and the red tailed shark will all be subjected to a cycling tank. You were told not to add any fish on that thread, but you still went and did it. Your lfs guy has not only got your money, but caused you a major problem! i.e. major water changes for the next month or three.