They are known to grow very slowly. Mine have grown about about an inch to two inches in the last year or so on blood worms, mysis, beefheart, massivore, krill, shrimp, etc. (whatever gets thrown in for the discus). I have wood in the tank, a pH of 6.3-6.6, a temp of 80-82 degrees, and low GH. They have plenty of hiding places, but there is LOTS of filtration. I never let the ammonia get high, and I keep nitrates slim to none. They live with my discus, and these are the only parameters I've been able to keep them alive for more than three months. I guess I've had them for at least 14 months. I have all three types of gold nuggest, and they all grow at different rates. The one with tiny spots grows VERY slowly like 3/4 of an inch a year. The one with the largest spots is a beefy guy probably growing more like 2 inches a year. So, it will depend on your fish and, of course, diet and water quality.