Let x be the weight of the fish that Peter caught. Then Ali and Joey caught 2*x and x+1 kg of fish, respectively.
So, x+ 2*x + x+1 =25
So, 4*x = 25 - 1 = 24
So, x = <<6=6>>6
Therefore, Ali caught 2*x = 2*6 = 12 kg of fish
#### 12