I would consider the goldfish to be one of the most misunderstood pets (and unlike most aquarium fish goldfish are a completely domesticated species: they don't naturally appear in the wild).

The problem with goldfish is that so many people think they know how to care for one. They may have had one as a child that lived for a few years in a bowl so they ‘know’ that's what you do.

You see depictions of goldfish in bowls all the time in the media which reinforces the idea that this is an alright way to keep them.

The truth is that goldfish bowls are animal abuse, and a simple Internet search will tell you that the recommended size for a goldfish tank is 30+ gallons (120+ litres) for the smaller varieties. (Some less reputable sites list 10 gallons which would only be suitable for a short time while they're a baby).

Why does the tank need to be so big? Well goldfish get big.

3-Pound Goldfish Found—How'd It Get So Big?

This is a photo from a news article about a man who fished up an adult goldfish. This is how big they are supposed to get. The fish you see in the pet shop are just babies and will grow quite rapidly for a year or two but then slowly reach their full size after around four years. Oh, and their lifespan is between 10 - 25 years depending on variety.

The article tries to be quite accurate but even it makes a few mistakes in implying that goldfish won't reach this size normally. The fact is that most goldfish don't reach this size due to neglect and abuse.

Imagine if 90% of dogs didn't make it to be two years old because most owners locked them in a broom closet to wallow in their own waste for days at a time.

When presented with this information a lot of people still like to believe myths like “they grow to the size of their tank” or brush the abuse off with “it's just a fish”.

While I believe goldfish take the prize, close runner-ups to most misunderstood pet would be hermit crabs (not domestic however), betta splendens (Siamese fighting fish) and pretty much all species of birds.