Its evidence. Go ahead and google it. I have a relative who is an underwriter and an agent with whom I've recently had contact about aquarium losses. A loss from an unexpected leak from a tank should not mean your policy is cancelled, unless you lets say hit it with a bat - or something negligent. Additionally, some policies require that you notify them that you have a large tank, etc. Just like if you have a Pit Bull or multiple other 'dangerous dogs'. If you lie about that on your application - you can be cancelled if you have an issue with one of those dogs/animals. Which is why - as a public service - I suggested anyone with a large tank speak and get it in writing - that your aquarium and damage to your property is covered if your tank breaks. Different states have different insurance regulations - so perhaps in some states, or with some cheap companies, they have in the fine print that they can cancel you. If you want insurance for your tank inhabitants - thats often NOT included in homeowners insurance without a special rider - or a policy from a different company