You can print them from here.
I have also used these cards for a version of Go Fish based on animal classes. Start with three cards each if you have four players or four cards each if you have two or three players. The remainder of the cards go in the center (the "fish pond"). Take turns asking any one other player if they have a mammal/reptile/etc. If it's a perfect match you place the pair face up in front of you. If they have the right class of animal but it's not a perfect match then you keep it and the next player goes. If they don't have any animals in the class you are looking for then the next player goes. The game is over when there are no cards left in the fish pond. The winner is the player with the most pairs.