Since you're from the saltwater side, you know how crucial calcium and hardness are! In freshwater, a fading and chipping shell usually means the water is too soft/acidic (low pH) or there's a calcium deficiency. Since it’s a small 2-gallon tank, parameters can shift fast. Try checking your pH/KH and adding some wondershell, crushed coral, or feeding them calcium-rich foods like blanched kale or snailo.