You may be lucky, or he simply hasn't grown up, or gotten bored or territorial.I have not run into that problem. but I do feed mine 2 times day. I will drop large sinking shrimp pellets maybe 2 at a time to make sure he is well fed. I put empty snail shells and some small rocks he likes to play with and rearrange. I will nock down his rocks so he stays occupied with rearranging them every so often like maybe once a month.
I fed mine too, and he was great for about a year and a bit, before the trouble started.