Keeping pets at home is not as popular as it used to be, says a report.
Less than half of families now have pets, but those who do prefer fish to dogs as they're easier to look after and don't need as much attention.
The study says one reason pet demand is down is because kids spend so much time playing with computers and mobiles that they are not as interested in pets.
But experts warn pets are good for you because they teach children how to put a vulnerable family member first.
The study, by Mintel, spoke to 25,000 people, and found that the number of people owning dogs has dropped by 26% over the last 20 years, but cats are still just as popular as ever.
This could be because dogs have to be walked every day, but cats can easily come and go through a cat flap.
But it is good news for pet fish who are getting more popular, with 16.5% of households owning then now, compared to 13.5% in 1985.
'Pets are good'
Dr Elizabeth Ormerod, a vet who has studied the bond between humans and animals, says children who grow up with animals find it easier to be understanding towards others.
The Pet Health Council says fish, guinea pigs and hamsters are good starting pets for children, but adults must supervise cleaning out and feeding.