How to convert .fna.gz files to .fna in a folder?

I would also like to convert all .fna to .fasta. 

Thanks in advance

I hope this will work.

    # Rename all *.fna to *.fasta
    for f in *.fna; do 
        mv -- "$f" "${f%.fna}.fasta"
    done

Or you can try

    find . -name '*.fna' -exec rename 's/\.fna$/.fasta/' \{} \;