Should "itheann na fir éisc" also be accepted?
Yes, since it doesn't specify whether it's one fish or multiple ones.
Reported, now a correct answer
Still not correct on the Android app
I will easily remmber this one because it is similar to "isca" in Portuguese.
What's the difference between "na" and "an" they both mean "the" so shouldn't "itheann an fir iasc" work also
“an” is for a singular, whereas “na” is for plural. “An fear” is a man and “na fir” is the men