"This child eats fish."
Translation:Dieses Kind isst Fisch.
We are not talking about natural gender here, but about the category of grammatical gender. Every noun has a grammatical gender, which has nothing to do with natural gender and simply should be learned together with the noun.
"der Hund" (dog) - masculine
"die Katze" (cat) - feminine
"das Pferd" (horse) - neuter
For those who are having trouble understanding this answer due to the lack of punctuation - Dieses: This (right here, as opposed to another child). Das: The/this/that (not to distinguish from a different child). So, it's a matter of emphasis... "Das Kind" would refer to the/this/that child in general, whereas "Dieses Kind" specifically means "This child (as opposed to another one). Right?