I have had 5 Tiger Barbs for the last couple months and this is what I have observed from them.
They like to swim circuits are the tank chasing each other. At least the males do. The one female that I have just sits under the heater and doesn't really do much until it's time to eat. She is very inactive otherwise.
My barbs love the light. They are non-stop swimming psychos when the light is on. When it is off they just kind of float prone in a strange vertical position.
I have noticed that the color fluctuates with activity. When it's feeding time or when they are fighting or chasing each other around the fins get a lot more red. 3 of them are albino and they are gorgeous to look at.
I kind of set my tank up so that there is a lot of room for them to jet around in. Yet still keeping it planted and having a large structure made out of pieces of slate for them to chill out in.
Other than that, I dunno, give them a varied diet. Mine consists of tropical flake, river shrimp, tubifex worms, bloodworms, algea waffers and shrimp pellets. I also have tossed some cucumber in the tank from time to time.
Are you using any aquarium salt? Freshwater fish still require electrolytes and such.
