Blue morphs

Question
I have a fresh water aquarium 3 feet X 1.5 feet X 2.5
I keep barbs and morphs  in that, i have a gravel with  2 filters one power filter and one undergravel filter
My blue morphs keep loosing their colour and start swimming erratically and die. before this i had the same problem with loaches . i have lost almost all by morphs execpt for 2 tiny ones i got recently, please help  

Answer
What form of barbs do you keep?  Many barbs are too large to be kept in this size of a tank.  How do you acclimate new fish?  This erratic swimming sounds to me like temperature or pH shock.  You should acclimate fish slowly in a separate container.  Fill container 1/2 full with the water the fish came in and slowly drip the new tank water into the container for 2-3 hours.  This will prevent pH and temperature shock.  Other issues could be that with morphs they could have a weakened immune system, or that there is too much ammonia/nitrite in the tank, or a number of other problems.  Good luck and feel free to ask more questions.