Fly Fishing: How to find & spot fish on the river

Fly Fishing: How to find & spot fish on the river

Fly fishing in New Zealand is unlike anywhere else on the planet. Freedom of access, coupled with the abundance of big fish in clear water, makes it any angler's dream to have the opportunity to fish such waters. From the tussock high country rivers of the lower South Island to the bush lined gorges of the North Island, the variety of waters is mind-boggling. However, no matter what the water may look like or where in the country you are, there are a few constant things to keep in mind - river structure and trout behaviour. 

The preconception that fishing in the South Island is you can just walk along a river bank and  fish will be there out in the open for all to see. Sometimes this is the case, but more often than not, it’s more likely the fish will be obscured by moving water, bedrock or poor light/shadow. This often causes problems for anglers of all skill levels, in particular the ones not yet adapted to reading water.. and if the fish are visible in open clear water,  it’s also more than likely you will be visible to them as you pace the river bank. 

River types, water colour and even fish colour can vary wildly between rivers in NZ. This classic 'gin clear' river does not necessarily make it easier to see fish.


To master spotting fish, you must first become a master at reading rivers and how they flow. Spring creeks and large waters aside, every river, no matter where you are on the planet, will have the same flow/bed structure: Riffle, Run, Pool. This is easy to identify as the shallow riffle eventually concentrates into the run which pours into the top of the pool, the rear of the pool often then turns into another riffle. The tricky part is then understanding where in each of these structures the fish will sit. 

After many intensive years spent on the water, both as a guide and with a rod in hand, it’s clear to me that Brown and Rainbow Trout purposely inhabit different areas of a river. There are exceptions for this, but it’s usually the case that Browns will feed in slow water, often off to the side of the main flow, whereas a Rainbow will prefer to feed right up in the main flow of a run, or riffle and only stray to the depths of a pool when food is abundant. Understanding this and knowing what type of fish are in the river, can go a long way to better understanding where to start looking for them. 

With the abundance of Rainbow trout in the North Island, all too often I have seen anglers just trudge into the water, up to their knees getting easy access to the centre of the river. However, should this river also hold Brown Trout, it’s more than likely you have just scared them off. Fishing in South Island rivers, with the majority exclusively brown trout, demands you be much more observant and cautious when approaching the river bank, because it's not uncommon to see a Brown tucked into the edge in just a few centimetres of water. 

Greg points out the nice run where we spotted and hooked into a great brown trout. Notice the depth and structure

Where to start

Becoming a master fish spotter means you must first approach the river with caution and also cover if possible. With our fish living the majority of their long lives in the same river or pool, they will usually be quite adept in their surroundings and notice when something unusual appears. The most common form of this is an object silhouetted against the sky, such as when you are walking atop the river bank. There is nothing more obvious and threatening to a trout than a shadow lurking over it from above and it’s likely it won’t stick around for long. 

Getting high can offer huge advantages when spotting fish. However it's important to remember that it may also make you easier to see too..

Where you stand can mean the difference between you seeing the fish, or it seeing you. So you want to try either to take cover against a backdrop that provides no contrast, or approach the fish in its blind spot, usually recognized as a 45 degree triangle from behind where the fish is sitting. Even if you can’t yet see a fish, keeping this in mind will ensure you're not spooking them before even getting the chance to spot them. 

Conditions on the river are always changing and the one thing you can do to improve your chance of spotting fish in most circumstances is invest in some good polarised glasses. Not your $20 pair from the gas station, but a pair made for fishing with a high contrasting lens (I prefer Brown) and suitable for most types of lighting. Learning to use the light conditions to your advantage will come with practice and time on the water, always remember though, just because you can’t see them, does not mean they can’t see you.

It's not all blue skies and sunshine, days like this are when you need to have quality glasses to cut out the glare and provide contrast.

The SSSM System

A few years ago when I came up with a fish spotting system called ‘SSSM’, this allowed me to focus on what mattered most, particularly when the conditions were tough. Not only does it allow you to systematically spot fish, but it can also allow you to catch fish blind when the conditions are not on your side. This system is just a rough guide and there are exceptions to the rule and it can be counter intuitive, however I have found it extremely useful: 

S - Structure

The beginning of every fish spotting endeavour, as discussed earlier the structure of the river will dictate where the fish lies. The more time you spend on the water, the more attuned you will become to the particular water you are fishing, as structure often changes from river to river. 

Structure firstly refers to the makeup of the water flow, but then also breaks down to what is in the river. Is there a rock, log or eddy that is breaking up the flow? This is particularly relevant when looking for Brown Trout. Or, is there a deep fast run with a slower current to the edge running over large boulders or rocks? Often a sweet spot for Rainbows. 

Approach every piece of water with ‘Structure’ as your first thing in mind and you will always have a reliable starting point to actually start looking where the fish may be. There will also be sections of a river that will hold no fish and once you know these, you can be more efficient in focusing on water with a higher chance of success. 

A clear example of good river structure with fallen trees into the corner of a slow flowing pool. Look hard to see the fish...

S - Shade

Next up comes a time when you are trying to locate fish within a stretch of water you believe they may be in. This is where ‘Shade’ comes in. Trout are incredibly adaptable and camouflage to their environment, but they are never 100% invisible, even though sometimes it feels that way. 

A trout will usually throw a different shade tone or shimmer against the bottom or in a run, depending on what angle you are spotting from. When I am spotting, I am looking into the water for something that does not look quite right and will scan vigorously between shade tones that look like they are slightly out of place. Sometimes if you are lucky, a fish could not be more obvious as it casts a dark mark against a light bottom. However counting on these ones alone, means you will be missing many more fish, usually ones you are more likely to catch. 

When spotting Browns, I am often looking for a darker shade. Again this can change, depending on the water type, when some fish take on a more silver or yellow tone. When it comes to Rainbows, the game changes as the best fish are usually very light coloured and give off a shimmer from the side. However from above their dark colored back maybe more similar to spotting a Brown Trout.  

As my saying goes, “The harder they are to see, the easier they are to catch”. So spend time looking hard, scanning and sometimes even throwing something in the water to test if it is a fish or not. 


Shades can vary immensely between rivers and even fish. These 2 browns although close togeather presented a entirely different colour in the water with the first barely visible with it's green back being the giveaway. It's important to 'key' in for what you're looking for on each river.

S - Shape

Now this is when things start to really take ‘Shape’. Once you have identified the shade that doesn't quite look right the next step is to identify the shape, depending on your assumption of the fish size in the river. The Shape test will often quickly rule out if the shade is a stick (too long and skinny), or a rock (too short and fat). But the one that will catch you out the most is the shadow cast by the sun, under a rock, on the bottom as these are often perfect fish shaped. It’s only on closer inspection or a failed catch you realise it wasn’t a fish after all.


As you can see the shape sitting at the back of the pool against the white gravel. We also confirmed this is a fish because of the eventual movement.

M - Movement

Counter to popular opinion, finally we have ‘Movement’. You will often hear movement is how people spot fish, but if that is the case, I can assure you they are missing 80% of the fish they walk past. 

Trout are amazingly efficient creatures and will usually locate a feeding position and stay there until disturbed or full. This means they sit still in one place, often in the point of least resistance and will swing out as food comes and then return to its holding spot. This swing is usually left or right but may also be up and down. Because of this, depending on the quantity of food coming down the river, the fish will spend more time dormant than it will moving. This is why I use ‘Movement’ as my last indicator.

Now, it does sometimes happen that the reason you notice a fish is a violent swing that catches your eye. That’s great, but don’t rely on it. The more effective way of spotting is to go through the Structure, Shade, Shape system first and if you're lucky, the fish may move during this and confirm your suspicions.

Sometimes just sitting and watching is the best way to confirm movement and feeding patterns


It is important to remember that every river has its own characteristics such as structure, water colour and gradient. So when spotting do keep these in mind if you want to be successful. It often takes spooking a few fish for you to key in on how they will look in the particular river, so don’t be afraid to get in there and test your assumptions. 

Once you get efficient at identifying Structure, Shade and Shape, you can scan through the water incredibly quickly, discounting whether it is a fish or not in just a few seconds so you can move onto the next spot. If you are lucky, Movement will speed this up even more but do not rely on it as a primary spotting tactic. 

After years on the water with a wide variety of anglers, I now believe that the best fish spotters excel through observation. It is not about how many fish they do see, but instead how quickly they can identify a potential object and then decide if it is a fish or not. Those that manage to do this with everything they see and quickly decide fish or no fish, spend more time moving through productive water and are ultimately more successful. To be the best, you should  confidently say “Everything is a fish, until you can prove it’s not!”.

One of those time where watching and waiting truly paid off. We weren't sure this was actually a fish at first, but on the first cast there was no doubt. The largest fish I ever guided on, a 12lb Rainbow!