Fischer sits next to 4 phonetic neighbors — Fisher, Finley, and Fletcher are the closest matches by sound. Most share Fischer's German-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"fisherman"
"pearl (via Scottish Maisie/Margaret)"
"weary"
"place of happiness"
"island meadow"
"friend; ally"
"Entertainment and Sports Programming Network"
"thornbush clearing"
"from Ireland, Irish woman (from Erin)"
"the younger one"
"To give thanks, to be thankful"
"She who has the power of the horses"
Similar sound: These names share phonetic patterns with Fischer — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have German origins, giving them the same cultural heritage as Fischer.
Rhythm: Fischer is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.