i would say do 50% then 25% changes but add filter primer between changes.
feed same quantity of food but in smaller pieces and one piece at a time over a few mins once the fish starts to lose interest stop feeding also dont be afraid to give smaller meals if the fish has good body shape and is not losing weight.
feed same quantity of food but in smaller pieces and one piece at a time over a few mins once the fish starts to lose interest stop feeding also dont be afraid to give smaller meals if the fish has good body shape and is not losing weight.