"Fish are small animals."
Translation:Ryby to małe zwierzęta.
why is "Kaczki są smaczne." correct then? is it because that there is no noun after the adjective "smaczne"? am i correct?
Yes. These are examples of "X is Y" sentences. If both X and Y are noun phrases, Y takes Instrumental. If Y is just an adjective, it takes Nominative.
Is "Ryby to są małe zwierzęta" correct? If I put that as an answer, it is counted wrong. Can you say "to są"?
This is not the most common construction and personally I think it sounds a bit clumsy, but technically it's fine and we did accept it in many sentences. Added here.
Still, I do not recommend it.
The plural of fish is fishes! You wouldn't say "Dog are small animals". Fishes are small animals is the correct English sentence, does that changes the polish sentence some how?