Getting to a healthy weight

[Fyre]

For those of you who may have read my earlier posts, you can skip the next paragraph

I recently adopted a male, 5yo ball python from a man who took awful care of him. This guy, when he handled Radi, would snatch him out of his cage and restrain him. He told me "he will bite you, so you have to be quick and grab his neck." I would have biten him too if I was picked up like that! I brought him home yesterday (along with the same, appropriate sized set-up he has lived in for his whole life). Already, he had chilled out and his taking handling like a pro when I picked him up properly. For feeding, his previous would drop two or three live mice into his tank about every two weeks and watch as he hunted them. The poor python, as a result of this, is thin and underweight.

Any suggestions as to how to bring him up to a proper weight without overfeeding him? I'm going to start by trying frozen and hope he takes it so I don't have to go live. I will if needed, though. Radi's previous owner said he wanted nothing to do with frozen, but I figured it's worth as shot since the rest of the advice he gave me was worth absoluetly nothing.

Right now, he is only about as thick as a paper towel roll (I uploaded pictures if anyone cares to take a look).

Please and thanks!

[I-KandyReptiles]

A weight would be best. Go pick up a kitchen scale (about $20).

A good idea is to feed 10-15% body weight every 5-7 days. It will be hard not to stuff him up, considering how thin he is, but stick to the schedule!

Is he eating rats or mice?

I'd try to switch him over to rats, if possible. It's a hassle to feed multiple mice at feedings.

If he won't eat f/t, just keep trying. It will take patience if he's strictly live.

[Fyre]

he is about 540 kg, so a rodent about 80kg grams should do, correct?

[elduki]

Feed the snake small meals frequently. In about a months time, you will see the difference.

[The Serpent Merchant]

he is about 540 kg, so a rodent about 80kg grams should do, correct?

you mean grams not Kilograms right?

The 15% rule works well for younger BP's but around this weight is where things can start to go wrong.

at 540 grams I would feed 60 grams of rodent (so a single 60 gram rat or 2x 30 gram)

Feeding every 5 days will help to put some weight on.