I have 8 tiger barbs in a 115 L aquarium with 5 long tailed danios, 2 neon clouds, and 3 platys. The tiger barbs sure are feisty, but they are very friendly to my other fish, including the long tailed ones. I also had neon tetras in there for a period, but the barbs picked on them. Thankfully I had a tank for them I set up. If you're thinking about getting barbs...do it!
About 6 months ago, my boyfriend and I set up a 75 liter aquarium consisting of 1 Bala Shark, 1 African Brown Knife, 1 Pictus Catfish a pair of Barbs...one Green, one Tiger. For 5 months they all got along really well. The barbs were great to watch. They were very energetic and played well with each other. Then, about 2 weeks ago, The Green Barb started getting a little too agressive with the Tiger Barb causing him to be stressed and weak. We took the Tiger Barb out to nurse him back to health, which he did. Meanwhile, we upgraded our tank to a 175 L aquarium and tried putting the Tiger Barb back in with the rest of them. Immediately, the Green Barb started annoyingly attacking (meaning nipping, nudging and raming) the Tiger Barb. The Bala Shark the Catfish tried to get the Green Barb to back off but he wouldn't. So, we thought that if we got 3 more Tiger Barbs, maybe the Green Barb would back off the seriously stressed out Tiger Barb. Instead, the Green Barb left one new Tiger Barb with a bloody fin, and another new Barb with a bruised bloody head. That was it. We took the Green Barb out and gave it away to a friend...alone.
Tiger barbs will display natural behavior in natural surroundings. Right now I have twenty of various ages in a 150 liter tank, and over many years of fish keeping I would say that this is the smallest setup I would recommend for tigers. Otherwise you will not see the full spectrum of their natural behavior. The colors male barbs display when driving females to spawn or sparing is just incredible. If your barbs are not doing this for you, they are not happy.
In my mind tiger barbs have it all for the enthusiastic fishkeeper. They are active (especially at feeding time!), beautiful and robust. Like all other contributors my great concern was which would be the best buddies for the barbs in my tank. In the end I opted for a shoal of neon tetras (the neons have been left in peace after a bit of initial bullying) and more controversially a red-tail black shark. Five minutes after the juvenile red-tail's intro into the tank he had a nasty nip to the tip of his dorsal fin by the alpha male of the barbs, who pursued him persistently. However, after the red-tail found his hiding place, a plant in one corner of the tank, things settled down and the red-tail and barbs co-exist peacefully, each aware of the danger the other presents. Barbs are wonderful fish to watch. Two of the males dominate the rest of the group and have spectacular chasing games at times. My children love the barbs and when the aquarium light first is turned on it as if the barbs put on a display swimming at speed up and down at the front of the tank. Six seems to be about the right number to keep these terrorists distracted from other tank companions. If you get the right number they are a superb fish to go for.
These pages have enough comments to give the reader a basic idea on the topic. Further comments are still very welcome (through the site's contact form) as long as they provide new and/or advanced information not yet discussed in the existing ones.