Swelling in the stomach due to gas

[ma3com]

Hello
After i put some food in my tank my nemo fish have a huge stomach and it is swim to the bottom the tank but it flow to the top of tank
What i have to do to make the stomach normal
I am sorry for the bad English
Plesae help me

 

[ma3com]

There is gaz in my fish

 

[EZMAC114]

What did you feed them and posting some pictures might help.