Each month, we'll post a guide to all fish available for you to catch that month in Animal Crossing: New Horizons.
A complete list of fish is also available, if you'd like an overview.
NEW FISH IN AUGUST

When: August-September (Northern) / February-March (Southern)
Time: 4 p.m. - 9 a.m.
Location: River
Price: 3,750 bells

When: August-October (Northern) / February-April (Southern)
Time: All day
Location: Sea
Price: 2,000 bells

When: August-November (Northern) / February-May (Southern)
Time: 4 a.m. - 9 p.m.
Location: Sea
Price: 3,000 bells
All Year in Both Hemisphere

When: Year-round (Northern and Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 160 bells

When: Year-round (Northern and Southern)
Time: All day
Location: River
Price: 160 bells

When: Year-round (Northern and Southern)
Time: 4 p.m. - 9 a.m.
Location: River
Price: 240 bells

When: Year-round (Northern and Southern)
Time: All day
Location: Pond
Price: 300 bells

When: Year-round (Northern and Southern)
Time: 4 p.m. - 9 a.m.
Location: Pond
Price: 4,000 bells

When: Year-round (Northern and Southern)
Time: All day
Location: Pond
Price: 1,300 bells

When: Year-round (Northern and Southern)
Time: 9 a.m. - 4 p.m.
Location: Pond
Price: 1,300 bells

When: Year-round (Northern and Southern)
Time: 9 a.m. - 4 p.m.
Location: Pond
Price: 4,500 bells

When: Year-round (Northern and Southern)
Time: 4 p.m. - 9 a.m.
Location: River
Price: 400 bells

When: Year-round (Northern and Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 180 bells

When: Year-round (Northern and Southern)
Time: All day
Location: River
Price: 400 bells

When: Year-round (Northern and Southern)
Time: 4 a.m. - 9 p.m.
Location: Sea
Price: 200 bells

When: Year-round (Northern and Southern)
Time: All day
Location: Sea
Price: 150 bells

When: Year-round (Northern and Southern)
Time: All day
Location: Sea
Price: 400 bells

When: Year-round (Northern and Southern)
Time: All day
Location: Sea
Price: 3,000 bells

When: Year-round (Northern and Southern)
Time: All day
Location: Sea
Price: 800 bells

When: Year-round (Northern and Southern)
Time: 9 p.m. - 4 a.m.
Location: Sea
Price: 15,000 bells

When: Year-round (Northern and Southern)
Time: All day (only rainy day)
Location: Sea
Price: 15,000 bells
Northern Hemisphere

When: April-August (Northern) / October-February (Southern)
Time: All Day
Location: Pond
Price: 300 bells

When: April-September (Northern) / October-March (Southern)
Time: All Day
Location: Pond
Price: 200 bells

When: April-October (Northern) / October-April (Southern)
Time: 9 a.m. - 4 a.m.
Location: River
Price: 5,000 bells

When: May-August (Northern) / November-Feburary (Southern)
Time: All day
Location: Pond
Price: ??? bells

When: May-October (Northern) / November-April (Southern)
Time: 4 p.m. - 9 a.m.
Location: Pond
Price: 800 bells

When: June-August (Northern) / December-February (Southern)
Time: 9 a.m. - 4 p.m.
Location: Pond
Price: 5500 bells

When: June-October (Northern) / December-April (Southern)
Time: All day
Location: River
Price: 800 bells

When: July-September (Northern) / January-March (Southern)
Time: All day
Location: River
Price: 900 bells

When: April-November (Northern) / October-May (Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 1,300 bells

When: May-September (Northern) / November-March (Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 1,500 bells

When: May-October (Northern) / November-April (Southern)
Time: 4 p.m. - 9 a.m.
Location: River
Price: 3,000 bells

When: May-October (Northern) / November-April (Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 2,500 bells

When: April-November (Northern) / October-May (Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 500 bells

When: May-October (Northern) / November-April (Southern)
Time: 9 a.m. - 4 p.m.
Location: River
Price: 800 bells

When: June-September (Northern) / December-March (Southern)
Time: 9 a.m. - 4 p.m./ 9 p.m. - 4 a.m.
Location: River
Price: 2,500 bells

When: June-September (Northern) / December-March (Southern)
Time: 4 p.m. - 9 a.m.
Location: River
Price: 10,000 bells

When: June-September (Northern) / December-March (Southern)
Time: 4 a.m - 9 p.m.
Location: River
Price: 15,000 bells

When: July-October (Northern) / January-April (Southern)
Time: 4 p.m. - 9 a.m.
Location: Pond
Price: 6,000 bells

When: June-September (Northern) / December-March (Southern)
Time: 4 p.m. - 9 a.m.
Location: River
Price: 10,000 bells

When: April-November (Northern) / October-May (Southern)
Time: All day
Location: Sea
Price: 1,100 bells

When: April-September (Northern) / October-March (Southern)
Time: All day
Location: Sea
Price: 650 bells

When: April-September (Northern) / October-March (Southern)
Time: All day
Location: Sea
Price: 1,000 bells

When: April-September (Northern) / October-March (Southern)
Time: All day
Location: Sea
Price: 1,000 bells

When: July-August (Northern) / January-February (Southern)
Time: 4 a.m. - 9 p.m.
Location: Sea
Price: 10,000 bells

When: April-November (Northern) / October-May (Southern)
Time: All day
Location: Sea
Price: 500 bells

When: July-September (Northern) / January-March (Southern)
Time: All day
Location: Sea
Price: 250 bells

When: March-November (Northern) / September-May (Southern)
Time: All day
Location: Sea
Price: 5,000 bells

When: December-August (Northern) / June-February (Southern)
Time: All day
Location: Sea
Price: 500 bells

When: June-October (Northern) / December-April (Southern)
Time: All day
Location: Sea
Price: 600 bells

When: July-September, November-April (Northern) / January-March, May-November (Southern)
Time: All day
Location: Pier
Price: 10,000 bells

When: May-October (Northern) / November-April (Southern)
Time: All day
Location: Pier
Price: 4,500 bells

When: May-October (Northern) / November-April (Southern)
Time: All day
Location: Sea
Price: 6,000 bells

When: July-September (Northern) / January-March (Southern)
Time: 4 a.m. - 9 p.m.
Location: Sea
Price: 4,000 bells

When: June-September (Northern) / December-March (Southern)
Time: 4 p.m. - 9 a.m.
Location: Sea
Price: 12,000 bells

When: June-September (Northern) / December-March (Southern)
Time: 4 p.m. - 9 a.m.
Location: Sea
Price: 8,000 bells

When: June-September (Northern) / December-March (Southern)
Time: 4 p.m. - 9 a.m.
Location: Sea
Price: 15,000 bells

When: June-September (Northern) / December-March (Southern)
Time: All day
Location: Sea
Price: 13,000 bells

When: June-September (Northern) / December-March (Southern)
Time: All day
Location: Sea
Price: 1,500 bells
Southern Hemisphere

When: November-March (Northern) / May-September (Southern)
Time: All day
Location: River
Price: 900 bells

When: October-March (Northern) / April-September (Southern)
Time: All day
Location: River
Price: 300 bells

When: December-February (Northern) / June-August (Southern)
Time: All day
Location: River
Price: 160 bells

When: December-March (Northern) / June-September (Southern)
Time: 4 p.m. - 9 a.m.
Location: River (Clifftop)
Price: 15,000 bells

When: December-March (Northern) / June-September (Southern)
Time: 9 p.m. - 4 a.m.
Location: River
Price: 4,000 bells

When: September-March (Northern) / March-September (Southern)
Time: All day
Location: River (mouth)
Price: 10,000 bells

When: December-March (Northern) / June-September (Southern)
Time: All day
Location: Sea
Price: 1,000 bells

When: November-February (Northern) / May-August (Southern)
Time: 6 p.m. - 4 a.m.
Location: Sea
Price: 5,000 bells

When: October-April (Northern) / April-October (Southern)
Time: All day
Location: Sea
Price: 300 bells

When: December-August (Northern) / June-February (Southern)
Time: All day
Location: Sea
Price: 500 bells

When: November-April (Northern) / May-October (Southern)
Time: All day
Location: Pier
Price: 7,000 bells

When: July-September, November-April (Northern) / January-March, May-November (Southern)
Time: All day
Location: Pier
Price: 10,000 bells

When: November-March (Northern) / May-September (Southern)
Time: 4 p.m. - 9 a.m.
Location: Sea
Price: 2,500 bells

When: December-May (Northern) / June-November (Southern)
Time: All day
Location: Sea
Price: 9,000 bells