Just like us a betta will not eat if he is feeling sick. Improper water paramaters will make him feel really terrible. And if he has nowhere to rest or hide then this will increase his stress. Bettas can go a week without food but three weeks means something drastic needs to change.
Felony theft is committed when the value of the stolen property exceeds $1000. Regardless of the value of the item, if it is a firearm or an animal taken for the purpose of animal fighting, then the theft is a Class 6 Felony.
That being said, they'll let you go and ban you from the store if you cooperate as long as you tried stealing under $100 worth because $100 or more is a felony offense.