Betta not eating, always lethargic. Why?

I do water changes at least twice a week, temperature of tank is set at 26 degrees. But he is still not eating. Having researched, i assume that its b

I do water changes at least twice a week, temperature of tank is set at 26 degrees. But he is still not eating. Having researched, i assume that its because he is an old fish, but is that really true or is he sick? Can someone help me with this issue ASAP. Please... Thank You

or:I do water changes at least twice a week, temperature of tank is set at 26 degrees. But he is still not eating. Having researched, i assume that its because he is an old fish, but is that really true or is he sick? Can someone help me with this issue ASAP. Please... Thank You

Tags:eating,always,