The water changes shouldn't be the problem. I do 10% every two or three weeks and 25% every two months. It depends on their diet, experiment with beefheart, feeder minnows, blood worms, brine shrimp and other meats. Careful of goldfish as mainly they are only good for RBP's every once in a while. I have two RBP's and one loses the redness in his belly one day and then two days later its bright again. They are for sale too. chicago. good luck with your RBP's