254 grams at 9 months is light to me. I wouldn't automatically say that's unhealthy though. Some just grow slower than others. I feed babies mice or rat pups every 3-5 days until around 6 months, then they start on weaned rats every 5-7 days. Then it's on to small rats. They are usually around 1000 grams by 1 year old. After that it's one small rat per week...