Fish Fancier's Ex-Girlfriend (Patreon)

He decided to break up with her.  He knew she was a sorceress but thought she'd take it like an adult.  Instead, she became hugely and insanely angry.  In a flash of magic, his world changed.  The first unwelcome discovery was that he was now swimming about in Jakri's huge aquarium.  He was free of her but now limited by the heavy plastic of her 2000 litre aquarium.  The fact that he was now half a fish wasn't unexpected given he was breathing easily underwater.  Swimming to the glass for the first time, he (now she) made another unwelcome discovery.  He was well and truly a mermaid and trapped within her aquarium until she saw fit to let her out.  At least, Jakri had left her some dignity in the form of a bikini top.

Photo Credits:
Woman: https://www.deviantart.com/wildplaces
Fish: https://www.deviantart.com/bouzid27