Deleting fish from inventory

You should be able to drag them to the left side of your inventory and sell them.

Just delete them like other house objects. 

Just drag and drop them to the left of your inventory (With the simoleons/sell button) 

I am having the same problem. Driving me nuts.

Can't delete, can't sell, can't drop ☹️

 The ONLY thing i have found for the UN-mounted ones, is to use them as bait fishing. As soon as fishing is done - stick them in the fridge.

Following up... I found the solution. WOOOO go me!

If you mounted the fish, PLAICE (heehee) onto a wall, head on into build mode click and sell :D 

@bandit999123

Can you post a screenshot of the error?