Personally, I think that would be too small for just for the 7-8 tiger barbs. I have 12 tiger barbs and a few of the older ones are about 3in. in length. At first they may be alright but as they grow you will have to find them a bigger tank. Also, I would be concerned about the pleco and cories getting enough food or being injured during feedings. My tiger barbs can be quite aggressive at times during feedings.
lex