Hi Goat,
In your experience, what is the likelihood of catching big fish on small flies? I will never go back to my early days of throwing a crawler into a pool; but sometimes miss catching the big trout. It seems like after a certain size they don’t waste their time on little bugs. If you were targeting bigger fish only, what patterns/sizes would you throw?


Thanks Pat

First question. Here is my non-scientific gut feeling.

I have to define what big is and put this into perspective. Lets assume we are talking “driftless trout big”. For me that is probably over 15″. Some say, at 12″ long, trout start to feed more heavily on larger forage(minnows, crawfish, sculpins, etc) and begin their growth to big. Some say 12″ is big. I would say 20″ or better is a trophy for our waters. Larger trout rivers of the West and big tail-waters like the Big Horn will have a different definition of big.

The likelihood of catching big fish on small flies is less than on big flies. For me, this is a simple calorie/metabolism/biological thought process. Small fish have little body weight to support. Their calorie needs for function are a whole lot less than trout with more mass. Eating 20-#20 nymphs may support a small trouts energy needs for an hour whereas it may only support a big trout for 5 minutes.  The energy expended to catch enough small bugs to support the larger mass may put the bigger trout in the red as far as the calorie bank is concerned. In other words eating small bugs may not be a sustainable feeding activity for bigger trout. I look at it this way, If a trout has to expend the same amount of energy to eat one french fry as it does to eat a quarter pounder with cheese. It will probably choose the quarter pounder if it can fit it into its mouth without choking. Simple right, expend the same amount of energy get more calories.

Now that being said, I have caught big fish on small flies. I love M&M’s. They taste good. When I was young and weighed a lot less, my mother would give them to me one at a time. They were rewards for being good. I could never get enough of them. I have never forgotten how good they tasted. Now, I can sit on my fat ass nicely toned posterior and eat a whole bag while I am on the couch watching TV. It takes very little effort. I do not have hunt them down or wait until I do something good to receive one to eat. Now, a trout on the other hand may also remember his or her childhood and the taste of a single mayfly nymph and how sweet and luscious it was. Under the right circumstances or when in competition with other trout for food, a large trout may also take a small fly. Many times, a single trico cast to a large feeding trout has resulted in an eat. Numerous times, during blanket hatches of tricos so thick you could not breath without a scarf across your mouth and nose, I have witnessed trout vacuuming the surface with their mouth open to eat small mayflies. These gluttonous trout, tail wagging and head above water, slowly swim the flat water and gorge themselves on the M&M’s of the aquatic world. Later in the morning they would cruz the weed mats where they expended little energy eating the millions of trico carcasses lodged along the edges.  They remember, or recognize the food, and are opportunists when the food is plentiful. But under the right circumstances they also will take one small fly. You can catch big fish on small flies.

Targeting bigger fish only, I would definitely take the streamer route and target the slower, deeper, undercut bank, rock pile, wood pile backwater structure. I would fish the lower end of rivers, especially now. Big trout will go out into the bigger waters to find big forage. The water temps are just fine for trout right now in the Mississippi, St. Croix, and other rivers. That will change as the water temps rise and the trout retreat to the cool water of their streams. The Walleye guys and gals at the dams at Red Wing and below have been finding some nice browns in the Mississippi. Patterns are wide and variable and range in size from #8 to 2/0. Buggers, Rabbit strip leaches, Todd’s Wiggle Minnows, Clousers and Murdich minnows, mouse and frog patterns. Fish at night. The bigger trout have turned nocturnal. I think science has proven that out. The number of trout in our regional systems that are over 20″ is small. Over 15″ is better. Right now there are a whole bunch of small fish in the systems from record reproduction the last couple of years.

Over the years I think I have experimented my way through most the phases or stages related to catching. They are all fun and have their positives and drawbacks. Eventually most anglers settle into the phase they enjoy most. Along the way you learn a lot about the fish, the forest the water and yourself. My current phase is the chillax phase. I like it, just like all the other phases of fishing for trout.

Thanks for the question Pat.