Which Fish?

So things got a little bit busy while I was on my lunch break.
And when I got back to my department, one of my coworkers who usually doesn't help in the department was attempting to help bag some fish for some customers. 

Sensing that I would probably be able to do the job faster, and to allow my coworker to get back to their department, I took over. 

And my coworker had done the thing where they wrote down the UPCs of the fish onto the bag before catching the fish.
Which is something I usually don't do because all too often, customers end up changing their minds about type and quantity of fish they want. So I usually wait until the end after I've caught all the fish before I write on the baggy which fish I caught.

My coworker had told me that the numbers were for platys and mollies and left to go help out elsewhere in the store.

The problem?
I don't always recognize the type of fish needing to be caught just by the UPC number alone. 
After all there are some fish I catch more often than others. 

But I didn't think it would be that difficult to find them.
After all, the customer was right there.
I could just ask them.

So I was like "Alright, which fish are we grabbing?" 
And the customer was like "Your coworker wrote them down on the bag." And then promptly got distracted picking out other fish.
But it's not like I knew which fish they were just by the number.
So I tried again. "Which fish are we grabbing?"
"They're on the bag." Was her response.
"There's just numbers on the bag, and I don't recognize them, so which fish were you wanting?" 
-I mean, I could have figured out the fish from the number, but it would have saved me time and effort and searching if she'd just respond.

But what was her response? "I don't know."

O.o
How can you NOT KNOW which fish you were wanting?
Did you not STARE at the Tank and PICK them out and tell my coworker I WANT TWO OF THESE? 
Therefore.
How can you not know which fish you were wanting??

*throws hands up in the air*
Sometimes I don't understand customers.
A simple "I wanted the black and white fish, the black fish, and those sunburst ones." Would have given me so much more help then. "I don't know, they're on the bag!" 

Ugh. Customers.

-Sarnic Dirchi