How do I know if my fish is dead?

[little-teddy-bear]

I forgot to feed him 1 day and he is not moving and is like grey. ( he is normaly blue.) i don't want to look because it is sick and i am crying because i think he is dead. Does it sound like he is?

He is a betta fish.

 

[ily.incubus]

one day without food wont kill him. he sounds sick but