OP, as Vypyrz said, that size is appropriate for an IJ, but if you can provide a more "proper" cage for the snake (Something like a Boaphile or Animal Plastics cage), it'd be better. Aquariums, with their screen tops, are both somewhat hard to secure properly, increasing your chance of escapes, and hard to maintain humidity and temperature in, making your job as a keeper more difficult than it needs to be.

Also, I'm just guessing that English is not your first language, so I'll try to offer this correction as gently as I can:

"Herbs" are things like rosemary, oregano, etc. "Herps" are reptiles and amphibians. Hopefully nobody gives you too much grief about that, but I figured I'd try to be helpful.