What should I do about hiding odessa barbs?

I have a 35 gallon tropical aquarium and in that I have 6 odessa barbs, 1 rainbow shark, two hoplo catfish and a BN pleco. Before I had two thick lipped gouramis but the first one died because of a blood clot in its body that exploded and the second one died because of stress from the bullying of the rainbow shark (I know i was a complete retard for mixing those two fishes). While the gouramis were still alive the barbs were swimming around everywhere but now that the shark cant bully the gouramis, he is bullying the barbs (whenever they come out). All the barbs are hiding in the back of my tank and they come out whenever it is feeding time and a few of them occasionally slowly come out only to be chased back into hiding by the shark. The funny thing is that there is no sign of stress at all, the barbs look more colorful than ever and whenever they come out and get chased, they dont form a shoal or anything like that. In my previous tank i had a group of 12 neons with the shark (when it was a juvenile) it still chased the neons furiously but the neons never minded, why arent the barbs the same? How can i encourage them to come out? The temperature is at 23-24 C, no ammonia, no nitrite and about 10 nitrates but its time for a cleaning today. I really would like my barbs to come out because they are by far the most beautifully colored fishes i have ever seen and its a shame that they hide always.