Relações Sub-aquáticas

When Raul discovers that the fish, he and his younger sister took care together has died, afraid that the death of the fish will tear them apart, Raul tries to find a way to hide the truth from his sister. After making a pros and cons list, he decides to go to an animal shop to buy a replacement. Always accompanied by his older sister that tries to reason with him. Too what lengths will he go to hide the death of the fish and protect the relationship he has with his sister?