Hydrolycus Armatus has stopped eating!!!

Hi guys, this is my first thread. My 3-4 inch armatus that I got from aquascapeonline.com has stopped eating. I got him last week on Thursday or Friday and he started eating right away. I fed him one rosy red every day until just two days ago where I fed him two. After that, the next day he stopped eating and today also. Should I be worried?

Here are some photos of him

Also what feeders are more safe for armatus that have lower thiaminase content? and when should I start training it to accept frozen foods like silversides