New, with new water snake

I just got a baby banded water snake. It had gotten into someone we know house, their dog tried to use it as a chew toy (not very successful) and one of them smacked the poor baby with their hand. Of course, I took the little guy out of there.It has been years since I've had a snake and she was not a water snake, so I am not entirely sure on the care and diet of this baby.First my most immediate question, the baby had a freak out moment earlier. S/he just started thrashing around with no direction, opened his mouth like he was going to bite but didn't. It ended fairly quickly. I have the feeling I just startled the poor thing but I want to be sure this doesn't sound like a symptom of any neurological damage (from being attacked earlier.) Is my little snake just scared or in trouble?Second, food. I read the sticky on what fish I shouldn't feed him, I plan on giving him guppies. How often do I need to feed him and how many guppies? Info I've found online has been unhelpful, as it all focused on adult care and not babies.Third, and of least concern, is there any way to tell by the body or tail if he's male or female? I have no idea really.

The first thing I would do is see if it's legal to own in your state. I know in PA any native wildlife is illegal.

I did and it's all legal.

I have no experience with them personally, but I'd imagine you'd feed them the fish like with garters and just offer as many live fish as it'll eat in one sitting about once a week

The best way to tell sex is by popping, but you'll want an experienced individual to do it. A 10 gallon would work for a baby. You can heat from above or below with a UTH on a thermostat. You want a basking spot of 85F and ambient temps around 75F to 80F. Since their diet consists mostly of toads, frogs, tadpoles, and fish they poop a lot, so the easiest substrates are paper towels or newspaper. I think paper towels look nicer. Provide a large water bowl, or even a rubbermaid container with water. For feeding time you can pick up some feeder minnows and just drop them in. Fish are digested much quicker than rodents, so you'll want to feed more frequently. I'd say every 5 days or so.

As for the thrashing, the snake was probably just frightened. It's a wild snake after all, and not accustomed to handling. It might musk or bite or just flail a bit when handled. If you do get bit, keep in mind they may have bacteria in their mouths and some species have saliva that acts like as an anticoagulant, so you may bleed a bit. Being wild caught, your snake may also have parasites l, which is something to keep an eye out for.