In my opinion, and from personal experience, males that will harm the pet of a wife/girlfriend/room mate are abusers in other ways; the same goes with females to males, or same sex relationships, just for clarification there - abusers come in many forms.
I won't go into that very deeply, but as a female that has lived through it, and is familiar with it happening to MANY others...
My goldfish are as important to me as many of your monsters are important to you.
When my ex & I finally split up after I managed to find the strength to get away from the abuse, he put dish soap in my tank killing all but one. That one survivor is still with me to this day and is now 9 years old.
As far as I'm concerned, it's animal cruelty and should be treated the same as harming a cat, dog, hamster, etc.
Anywho, stepping off my soapbox.