Prasheen

A week ago i bought 4 tiger barbs n from the time i bought them they stay in 1 corner of my 120g tank all day, its only when i put off all the lights at night that thay start swimming around the tank, i really dunno wats wrong i have 4 kribensis, 2 bala sharks, 1 pangasius shark, 1 gourami, 1 pike-nosed gar, 2 swordtails, n inserted my betta yesterday. R tiger barbs nocturnal? Or are they being threatened in some way?

hazfish

The only thing I can think of is that you may need a few more tigers. They are a schooling fish and tend to do better in groups of six or more. With such a large tank, you may need to buy at least four more to give them a school of eight. I have a school of three tigers that do just fine, however they are in a 29 gallon tank, and are the largest fish in the tank...they share the tank with a couple of cory cats, three gold barbs, three debauwi cats, and a yo-yo loach.

ChrisRamo

Hazfish is right, you should get a few more tigers especially if you have a tank that size!
Not only does it make them more confident in a group but it helps to get rid of their fin nipping behaviour they have