Are these sentences incorrect?

1.They were watching television when I telephoned.
2.They bought three fishes at the market.

Question

Are these sentences incorrect?

1.They were watching television when I telephoned. 
2.They bought three fishes at the market.

Answer

1.They were watching television when I telephoned. CORRECT
2.They bought three fish at the market.

Answer

1.They were watching television when I telephoned.
2.They bought three fish at the market.