Cant really tell from the 1st and 2nd pics but the 3rd one is better. Given that water weighs 1kg per litre it's fair to say that a 2 litre bottle of coke would weigh well over 4lbs and seeing as the fish density would be greater than water I wouldn't doubt it made 7lbs on the scales. And even if there was a bit error in the scales, who cares! Cracking fish mate well done