Transparent Betta

Question

Betta   Recently, my Betta fish has been acting more lethargic and his body has turned almost entirely transparent! He is usually entirely blue. I tried to capture it in the attached picture, but it was difficult to get on film.
He is in a three gallon tank. He has been eating some days and not others.

Do you have any advice?

Answer
Alexa,
There should be gravel in his tank. I think that he is like this because his water is too cold. He is a tropical fish and needs his water to be at 80 degrees at all times. I would also add some gravel. Once you have him in the proper home, with gravel and a heater you should see a huge improvement. I also notice some fin rot and clamped fins. When you add the gravel and heater, add some aquarium salt to his water. This is help with the fin and tail problem.