Answer:
There are 2 dogs
Explaination:
If there are 28 eyes in total,
Dogs- 4 eyes
Chickens- 8 eyes
Fishes - 16 eyes
In total they have 28 eyes
if there are 16 legs,
Dogs- 8 legs
Chickens- 8 legs
Fishes- 0 legs
So,
2 Dogs
4 Chickens
8 Fishes
( the problem even said that there are twice as many fish as chickens)