Learn Spanish (Latin America): Mi abuelo pesca a menudo.

Yes, you can! Frequency adverbs like a menudo are flexible in Spanish. You can place it at the end like in this sentence, before the verb (Mi abuelo a menudo pesca), or even at the very beginning (A menudo mi abuelo pesca). Putting it at the end is very common and natural.

Why are there two words (a menudo) for just "often"?

A menudo is a fixed phrase. On its own, the word menudo can mean "small" or "insignificant", but when you put a in front of it, the phrase always means "often." You just have to learn them together as a pair!

Is the verb pesca related to the Spanish words for fish?

Exactly! Pesca is the "he/she/it" form of the verb pescar (to fish). It shares a root with pez (a live fish in the water) and pescado (a fish that has been caught and is ready to eat).

Could this sentence also translate to "My grandfather is fishing often"?

Yes, the simple present tense in Spanish (pesca) can sometimes translate to "is fishing" in English. However, because we are using the frequency adverb a menudo, it clearly describes a habit or routine, making "fishes" the best English translation here.