In health class I learned that the common result of constipation in people is not enough fiber in the diet. We can eat fruits and vegetables to prevent getting constipated. Could this be applied to goldfish as well?

well what you do for goldfish is you feed them deshelled peas 2-3 times a week

Peaches is right. Peas are an excellent source for constipation in gf. A diet rich in peas and veggies will help them to avoid this. However remember protein is an important factor as well.

It worked really well for my goldfish!