What stainer should i use for a wooden aquarium for tropical reptile?

so i recently aquired a dresser from my grand parents to make it into a aquarium for my chinese water dragon. i striped all the drawers and any wood work inside of it until it was a hollow box. now i need to stain it so the wood wont mold or get destroyed from all the humidity. any hints on what i should use to protect it? also something where it wont be hazardous to my pet =). thx for any info