Tiger barbs acting strange

[greenwoods1992]

I just put 6 tiger barbs into my 40 gallon tank and for three days now 2 of them have been doing back flips and spinning around, any idea what I can do to help this

 

[serena00]

What else is in this tank? I have one albino tiger who does this too. It's been 2 months and he still does weird things but eats and swims fine.


36g semi-aggressive
20g community
5.5g betta/ghost shrimp
3g betta
2g fry