I thought I'd make this post as it might be helpful to some people. Below is a list of patterns which you can get from Wendell and what to give him to get them but this is from the Prima Guidebook and people have already said that some of these are wrong, so I'd be grateful if you guys could point out the errors for me so I can fix it.
Angelfish - Field of Flowers
Apple - Coloring Nook
Arapaima - Nothing! (Inedible)
Arowana - Pitfall
Barbel Steed - Vertical Street
Barred Knifejaw - Curved Track 3
Birthday Cake - Self Portrait
Bitterling - Intersection
Black Bass - Grass
Blue Candy - Coloring Boy
Blue Marlin - Iron Floor
Bluegill - Street Corner 2
Sea Bass - Horizontal Track
Carp - Vertical Street
Catfish - Mystery Circle C
Char - Street Corner 2
Cherry - Coloring Resetti
Cherry Salmon - Street Corner 1
Chocolate Heart - Chocolate
Clownfish - Curved Track 4
Coconut - Coloring House
Coelacanth - Nothing! (Inedible)
Crawfish - Rhino Beetle
Crucian Carp - Ground
Dab - Curved Track 1
Dace - Street Corner 1
Dorado - Money
Eel - Mystery Circle D
Elegant Mushroom - Memo
Flat Mushroom - Memo
Football Fish - Stairs
Freshwater Goby - Mystery Circle A
Frog - Water Puddle
Gar - Gyroid
Giant Snakehead - Manhole
Goldfish - Money
Green Candy - Coloring Girl
Guppy - Field of Flowers
Hammerhead Shark - Nothing! (Inedible)
Horse Mackerel - Horizontal Track
Jellyfish - Outer Space
Killifish - Water Puddle
King Salmon - Treasure Chest
Koi - Footstep
Loach - Mystery Circle B
Lobster - Red Carpet
Moray Eel - Pitfall Warning
Napolean - Nothing! (Inedible)
Neon Tetra - Field of Flowers
Ocean Sunfish - Nothing (Inedible)
Octopus - Curved Track 2
Olive Flounder - Curved Track 1
Orange - Coloring Pelly
Pale Chub - Street Corner 4
Peach - Coloring Rover
Pear - Coloring K.K.
Pike - Stone Paving
Piranha - Cracked Ground
Pond Smelt - Intersection
Popeyed Goldfish - Money
Puffer Fish - Forbidden Sign
Rainbow Trout - Street Corner 3
Rare Mushroom - Picture Frame
Ray - Treasure Chest
Red Candy - Coloring Girl
Red Snapper - Curved Track 3
Red Turnip - ? Block
Round Mushroom - Memo
Salmon - Red Carpet
Butterflyfish - Vertical Track
Sea Butterfly - Outer Space
Sea Horse - Curved Track 4
Shark - Nothing! (Inedible)
Surgeonfish - Horizontal Track
Sweetfish - Street Corner 3
Tuna - Iron Floor
White Turnip - Brick
Yellow Candy - Coloring Boy
Yellow Perch - Street Corner 4
Zebra Turkeyfish - ! Sign
Angelfish - Field of Flowers
Apple - Coloring Nook
Arapaima - Nothing! (Inedible)
Arowana - Pitfall
Barbel Steed - Vertical Street
Barred Knifejaw - Curved Track 3
Birthday Cake - Self Portrait
Bitterling - Intersection
Black Bass - Grass
Blue Candy - Coloring Boy
Blue Marlin - Iron Floor
Bluegill - Street Corner 2
Sea Bass - Horizontal Track
Carp - Vertical Street
Catfish - Mystery Circle C
Char - Street Corner 2
Cherry - Coloring Resetti
Cherry Salmon - Street Corner 1
Chocolate Heart - Chocolate
Clownfish - Curved Track 4
Coconut - Coloring House
Coelacanth - Nothing! (Inedible)
Crawfish - Rhino Beetle
Crucian Carp - Ground
Dab - Curved Track 1
Dace - Street Corner 1
Dorado - Money
Eel - Mystery Circle D
Elegant Mushroom - Memo
Flat Mushroom - Memo
Football Fish - Stairs
Freshwater Goby - Mystery Circle A
Frog - Water Puddle
Gar - Gyroid
Giant Snakehead - Manhole
Goldfish - Money
Green Candy - Coloring Girl
Guppy - Field of Flowers
Hammerhead Shark - Nothing! (Inedible)
Horse Mackerel - Horizontal Track
Jellyfish - Outer Space
Killifish - Water Puddle
King Salmon - Treasure Chest
Koi - Footstep
Loach - Mystery Circle B
Lobster - Red Carpet
Moray Eel - Pitfall Warning
Napolean - Nothing! (Inedible)
Neon Tetra - Field of Flowers
Ocean Sunfish - Nothing (Inedible)
Octopus - Curved Track 2
Olive Flounder - Curved Track 1
Orange - Coloring Pelly
Pale Chub - Street Corner 4
Peach - Coloring Rover
Pear - Coloring K.K.
Pike - Stone Paving
Piranha - Cracked Ground
Pond Smelt - Intersection
Popeyed Goldfish - Money
Puffer Fish - Forbidden Sign
Rainbow Trout - Street Corner 3
Rare Mushroom - Picture Frame
Ray - Treasure Chest
Red Candy - Coloring Girl
Red Snapper - Curved Track 3
Red Turnip - ? Block
Round Mushroom - Memo
Salmon - Red Carpet
Butterflyfish - Vertical Track
Sea Butterfly - Outer Space
Sea Horse - Curved Track 4
Shark - Nothing! (Inedible)
Surgeonfish - Horizontal Track
Sweetfish - Street Corner 3
Tuna - Iron Floor
White Turnip - Brick
Yellow Candy - Coloring Boy
Yellow Perch - Street Corner 4
Zebra Turkeyfish - ! Sign