I like to consider myself a rational thinker, yet changing my mind about any number of long-held views isn’t easy. That I can do it at all may be partly down to my time many years ago obtaining a university degree. While I’ve learnt that such qualifications certainly don’t define me (or anyone else I know), one thing uni taught me was to accept that hard evidence would, on occasion, derail what I confidently believed. I could plead all I liked with the tutors and examiners about what I reckoned was the case, but if I didn’t provide the proof, they weren’t interested.

I’ve attempted to bring the same thinking to my fishing, but as I said, it’s not easy. There is something comforting about an apparently fishy fact. The slippery little buggers are hard enough to undo as it is, so if you can establish to your satisfaction that, say, they don’t bite on a falling barometer, or they never knock back a flying termite, great… except that example is immediately a contradiction (termites love to take flight on a pre thunderstorm falling barometer). Still, you get where I’m heading: when you think you’ve got one little piece of the puzzle solved, it’s hard to let it go.

Over time, some firm beliefs have slipped. I’ve discovered you can in fact catch trout in water that’s too dirty to see the bottom when standing knee-deep; or that rising lake levels can actually be bad if they’re rising too fast, or that Stimulators can sometimes beat a Royal Wulff.

Speaking of flies, it’s decades since I finally accepted that Scintilla Stick Caddis are deadly, despite their bland appearance. Yet it’s only been months since I realised I really like Magoos. Why so long? Partly it may have been some sort of inverse snobbery, whereby if competition fishers liked them so much, I wasn’t inclined to. Partly, I thought it was a stretch to identify a Woolly Bugger with a big tail as a new fly. Then there was the not unreasonable and related thought that Magoos didn’t do anything that pre-existing flies didn’t do already.

A good fish or several can change your mind about a fly… in this case the Magoo.

You can guess that several very good lake trout recently – each caught on quite difficult public waters – have changed my mind on all that, to the point where I feel anxious without a Magoo (particularly an olive version) in the box. I now watch the flickering/ fluid motion of a well-tied Magoo with newfound expectation.

In terms of the biology of the fish themselves (and the things they eat) I’m still learning. One evolving lesson is the ability of at least some species I chase, to detect flies in seemingly impossible conditions. Forget water discoloured to the point where I can’t see my boots when knee deep. I’m now talking about water so turbid, I can’t see my fly a few inches below the surface – and then overlay that with after dark. Even for the big eyes of estuary perch, finding a fly in extremely murky water and at night seems a task too far. Yet one of my fisheries scientist mates was telling me recently of research where blindfolded fish found prey better than those with full vision but a disabled lateral line.

Caught in muddy water at night – the lateral line working its magic?

This fits with something Rod Harrison told me years ago about watching yellowbelly tracking the path of his Woolly Bugger like a bloodhound on a scent, well after the fly had left the water. Rod thought of this as the fish following the fly’s sonic signature. Coming from anyone else, I would have considered this observation a stretch, to say the least. Now, it sits nicely with this lateral line stuff. I’ve always known that lateral lines on fish are a thing, and that they’re no doubt a useful sensory accessory. But the idea that in some situations lateral lines may be a more important than eyes, is something I simply wouldn’t have contemplated until a few weeks ago.

So now, I’m rethinking fly visibility limits again; or more to the point, fly detection limits, as it seems sometimes, vision has little to do with it. I look back at fish I’ve caught in can’t-see-my-fingertips water; catches which at the time appeared miraculous, but which seem less so now when I consider that lateral line experiment.

A discoloured estuary and fading light… but I’m more willing to give it a go now than I was.

I’m already fishing discoloured water with more confidence, at least on an intellectual level. That is, I know from the science that fish can find my fly better than eyesight alone would suggest. Don’t misunderstand me though, part of me still ‘reckons’ that if the water is too dirty, I won’t catch anything. Truth is, I’m probably going to have to convert a few more muddy water successes before I’m really persuaded.