goby help

i'm not sure how long they take to change their stripes but when i first got mine he was little not more than an inch or so and his stripes had already changed. when i bought him i really didn't know what i was buying the guy at the lfs talked me into it. i was shocked as to how big he got. when i gave up my tank a friend of mine took him and you talk about imposible to catch. we had to take out all the rock and still had trouble.