[Sneaky]

Hi there,
I agree with MyBird theres often more at play than just health or age.

If you can answer the following questions, we can help to determine what exactly is wrong with your betta, and what you can do to help it.

What size is the tank?

How often and what percentage do you change water?

Is there a filter? If yes, how often do you change the media? Do you change the media at the same time as you do a water change?

Do you ensure the water is same temperature when you change it? Do you use your finger or a thermometer?

What temp is the tank?

Have you done water tests for Ammonia, NitrItes, and NitrAtes? Is so, please post exact number results?

How long have you had the fish, how long has the tank been set up?

Do you add anything to the water? Conditioners? Dechlorinator? Ph adjuster? Anything else? Salt etc.

Finally, what are the symptoms? Any signs of wounds or injuries? Any trouble breathing - breathing fast and heavy or super slow? Is he eating? What are you feeding him, how often and how much?
When you say losing color what do you mean? Is the fins turning white?
Do you see any ragged edges or fuzziness? Is it starting at the end of the fin and moving up the fin?

Are there live plants in the tank?

Answers to all these questions will help me to deduce what is wrong with your fish.