Would a Betta fish be good for my Grandmother?

She is almost 80 and her birthday is in two weeks, I think a fish would spark her interest, and provide entertainment. She already has a dog that she loves(that my mom and I got her). So I think a fish isn't a problem for care( she also has a care giver) but she isn't that interested in TV anymore. She also loved watching fish at restaurants. I don't want it to be a big thing cause change makes her nervous, so are there any other cool yet small fish besides Betta? Or are Betta even a good for her??