Last week I wrote about my daughter’s new designer dog which, in eight weeks, has grown to the size of a garden shed and is now costing £2m a minute in food and satellite tracking devices. Small wonder, I concluded, that the people of Britain are now replacing their dogs with pet fish.

The thing is, though, that ever since I wrote that, it’s been bugging me. Sure, I can understand that a dog is jolly expensive, but replacing it with a fish is like replacing your house with a potato.

I have two and they are utterly, utterly useless. They don’t come when they’re called, they don’t bark at strangers, they won’t fetch sticks, they’re not cute and being fairground goldfish, I’m fairly sure they wouldn’t be delicious either. Honestly, it’d be more rewarding to own a pet rock.

And don’t think things improve if you move up the evolutionary scale and go for a koi carp. My dad did that, and spent many happy hours watching them gliding around his garden pond, gorging on the psoriasis flakes that fish call food.

Then one Christmas I bought him half a dozen “ghost koi” which looked very splendid in the tank at the pet shop. Unfortunately, in my dad’s pond we learnt why they are called “ghost” fish. It’s because they are completely invisible. And what’s the point of a pet you can’t see?

Sadly, I also discovered that in the fish world they are the SAS among carp, approaching their prey silently and killing without pity or remorse. So within a day, all my dad’s beloved orange fish were upside down on the surface, leaving him with a pond full of apparently nothing at all.

My advice then is simple. If you want a fish, get it from the chip shop. If you want a pet, look elsewhere.

Happily, I’m able to give you a few pointers because over the years, I’ve owned, loved and inadvertently killed nearly every animal on the planet.

One little thing I can tell you straight away is that you should never name a brace of animals after a famous pairing. I did this as a child and after Gilbert and Squeak died, I ended up with Bubble and Sullivan.

I became so fed up with all my pets being killed, in fact, that I eventually bought a couple of tortoises, which came with a hardened outer shell and a life expectancy of 2,000 years.

Sadly, however, and for reasons I don’t fully understand, given that they had a top speed of one mile a year, they managed to escape into a field of wheat that was then harvested. Even to this day, I open each packet of Rice Krispies with fear and trepidation.

Of course, this endless cycle of life and death taught me a great deal about the ways of nature and I was keen that my children should be similarly educated. So I recently bought them each a cute little guinea pig.

Just a week later, however, I came home to find them gone and a fox-sized hole in their cage. I should have told the kids the truth, that they’d been torn apart, for fun. But I didn’t have the heart. So I invented a pathetic story about how they’d escaped and gone to live near a stream in the sunshine, with some water voles.

Great. But the next day, I found half of one of them in a hedge and fearing the children might find the rest of him, or his mangulated mates, I had to call in a team of helpers to go through every bush and thicket within a radius of two miles looking for legs and arms.

We failed and I’m still frightened that one day, when they’re playing hide and seek, there will be a shriek as one of the children discovers a severed head, and in doing so, exposes my sunshine and water vole story as a lie.

I wouldn’t mind but I loathe guinea pigs unless they’re on a spit. And rabbits. Rodents of this type are just fish with fur. They’re utterly, utterly useless too.

The best pets I have are my donkeys. Unlike my wife’s horses, which break down all the time, and lose their shoes, and are frightened by puddles, and plastic bags, my donkeys are totally reliable in all weathers, they come when you call them, and they hee-haw when they see a burglar.

But that said, there are some drawbacks, compared to dogs. If, for instance, you invite them inside to sit by the fire on cold winter evenings, they do take up a lot of space and, of course, they can’t be house trained.

So what, then, with my wealth of experience of the animal kingdom would I recommend if you don’t want a dog any more? Well not a cat, obviously — despicable animals, the four-legged equivalent of a footballer’s wife: pretty, well groomed and clean but, fundamentally, only after your money.

You want something that loves you, something scary for thieves, something that doesn’t make too much of a mess and something, above all which costs almost nothing to buy and run. Well how about a rat? Rats get a lot of bad press. Sure, they did kill half the world’s population once but it wasn’t their fault. It was the fleas that lived on their backs and it was a long time ago.

Today’s rat can be taught to respond to its name, if you go for a male, it will clean up after itself and it will be very loving. And what’s more, you can use a rat’s back to grow yourself another ear.

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