Crisp also felt that had he swam a personal best in the final he would have made the podium with a bronze at least.
"My PB would have got me bronze so I'm pretty annoyed with myself really," Crisp said. "It didn't quite flow today and I don't know why.
"It would help if I was about four years younger. I found it hard to find a rhythm. It was wasn't quite there today and it's disappointing."
ParalympicsGB currently have 29 gold medals.