I don't think it's full grown yet, unless you bought it at a larger size already, I have had mine for 2 years and it is almost 5"s and is still not full grown. It is a mature male adult, but I wouldn't say done growing.Haven't had any probs with ours, and I think the with caution is because of exactly what treylane said, although mine's now full grown and hasn't gone after anything but food. Have had ours since last October. Took care of the pyram snails for us the first 2 months (the point of purchasing him).