White Specter Crayfish

So several weeks ago some friends and I were at dinner and next door was a petco, afterwards I insisted we go in for free zoo time. I immediately head to the fish zone to check out the bettas and aquarium supplies. I noticed a sparsely populated tank with a few dead fish and a white crayfish laying on its back in an "I'm obviously dead" position. When an employee approached me I voiced my displeasure and pointed out the rotting crayfish. To which she replied he wasn't dead at all, stuck her arm in poked it and it definitely was not dead!
Apparently the week prior someone had returned him. While in their care all I can assume is something else in the tank saw him as a snack. He was missing his left big claw many of his feelers, the ones he did have left were black and mangled . I have several tanks already set up and had an extra 5 gallon not in use. I asked her if because it was so severely injured would they sell it discounted. I don't have experience with crayfish but I felt as if he'd have a better chance with me and was prepared to purchase him. She was great and said I could take him as an adoption. I won't lie, as determined as I was to get him better, he was so mangled and pathetic I honestly didn't think he'd make it. He could barely move and I couldn't tell if he was able to grasp his food to even eat. He spent most of his time on his back or side. Finally he molted last Sunday after having him about a month, I left the shell for him to eat and it's only one week later and he's molted a second time. His legs are coming back and his big claw is well on its way.
I know it's a long story, but I really just thought I was giving it a peaceful last few days before dying. I've read and read and asked pet people about his care. But I get different information from different people and different sites. I just want to know if I'm caring for him ok. He's in a 5gal tank with my snail who had been sick, they mostly keep to themselves but my snail occasionally plows by him to get where he's going. He has a Filter, heater, weekly water tests and he gets pellet food formulated for crustaceans.
What are the ideal water parameters for a crayfish?
How often do I feed him? I've been feeding twice a day.
I've been doing weekly water changes for him when I do my other tanks, is that ideal for him as well? Or should it be more/less often?
How often will he molt and should I always leave it for him to eat, or only until he's grown everything back?
Is there anything I can do to speed his recovery? Or am I doing anything wrong?
I live in an apt and am already pushing the rules by having as many tanks as I do, but I get by ok by not being a nuisance tenant. If cared for well, can he be ok in a 5 gal tank? I don't know what will happen to him if I give him away, but I don't know if my property manager will allow me to upgrade tank size. I want to be a good owner, I want him to recover fully too. But I'd be remiss to say I have much experience... Please no lectures or scolding. I'm here to find out how to provide the best care for my animals.

 

Looks like a rather young cray, just keep doing what you're doing. When he/she molts a few times I believe the missing parts will start regrowing as well. Feed high calcium foods, perhaps throw in an earth worm here and there along with some leafy greens and I bet it will be quite happy. As it grows you may want to think about giving it a new home/owner but for now just focus on letting it heal.

 

I love stories like this and admire the people who go out of their way to help these critters so well done, shes well on he way to recovery moulting twice is s sure thing your on track, leave all the moults in she will eat the much needed calcium, she must be young to moult so close together but as she gets older it will go to a month then 6 weeks and so on to as long as 3months, clean fresh water is a must for these guys once a week is fine feed him as you are but also offer some spinach or any veg, he will need a bigger tank 10 gallon should do it, don't give him away after what you've done, it's possible for him to share a tsnk with fish as long as they are mid to top feeders, cray are opportunist so wount actively hunt them down, as Demeter said don't change anything and come back with any concerns,
By the way make sure the tank as a lid

 

I love stories like this and admire the people who go out of their way to help these critters so well done, shes well on he way to recovery moulting twice is s sure thing your on track, leave all the moults in she will eat the much needed calcium, she must be young to moult so close together but as she gets older it will go to a month then 6 weeks and so on to as long as 3months, clean fresh water is a must for these guys once a week is fine feed him as you are but also offer some spinach or any veg, he will need a bigger tank 10 gallon should do it, don't give him away after what you've done, it's possible for him to share a tsnk with fish as long as they are mid to top feeders, cray are opportunist so wount actively hunt them down, as Demeter said don't change anything and come back with any concerns,
By the way make sure the tank as a lid

Thank you, this is so encouraging!

 

Looks like a rather young cray, just keep doing what you're doing. When he/she molts a few times I believe the missing parts will start regrowing as well. Feed high calcium foods, perhaps throw in an earth worm here and there along with some leafy greens and I bet it will be quite happy. As it grows you may want to think about giving it a new home/owner but for now just focus on letting it heal.

Thank you, I bought food for crustaceans specifically that s/he can't seem to get enough of but I'll start giving it some veggies!

 

Thank you, this is so encouraging!

Oh and the tank does have a lid, you referred to it as sure, do you know how to sex crayfish? I mean I had to name it peg leg Joe because I'm immature but I really don't know what sex it is