Translation:The children are touching an orange fish.
Well, "dotykać" takes Genitive, so "ryby" may only be singular, 'cause plural Genitive would be "ryb".
Moreover, "pomarańczowej" is definitely not any plural form, it's Genitive singular feminine.
how come in the beginning it was ok to translate singular fish without the article but here it's not accepted?
Probably the other sentences could interpret "fish" as "fish meat", but that would feel very weird here.
Shouldn't it be "Pomarańczową" and "Pomarańczowej" only if it was a negation?