We all had to start somewhere and we are all still learning constantly so no need to be nervous
I think you need to study more Koi designs and it probably needs more shading (I drew I don't know how many Koi's before I grasped this lol)
I put a variation in my portfolio I think it's good to show to show you are versatile
Your lines are good and you have a good basis, just keep studying and looking at all kinds of designs, subject matter, styles.
Hope this helps you