Colton Kelly is a Farlows Content Creator and fly fishing guide based in Wales. He has recently returned from a sea trout fishing trip on the Rio Grande in Argentina for the first time. In this article, he talks packing, learning and adapting.
Suppose you have an upcoming trip to Argentina to fish the Rio Grande for the first time or you're thinking about going in the future. In that case, you might be pretty apprehensive or curious regarding methods, tactics, sea trout tackle and the travel. I hope below will help prepare you for your trip, wherever the wind takes you on the Rio Grande.
Colton's Guide to Sea Trout Fishing Argentina
Having wanted to fish the most famous sea trout river in the world for many years, it finally happened in January 2025. I’ve been lucky enough to have travelled around the world fly fishing and fished in some of the most beautiful countries and islands, but this was by far the longest travel I’d done, and boy, was it worth it.
I took the train from West Wales – Heathrow, Heathrow to Buenos Aires – Buenos Aires to Ushuaia – Ushuaia – Rio Grande Aurelia Lodge. Altogether around 2.5 days from start to finish.
When you arrive in Buenos Aires, you’ll be greeted by 30 degrees plus, and leaving the British winter is much appreciated, but don’t get used to it, as the following day you’ll be heading down to the closest point to Antarctica! Flying into Ushuaia, the scenery is just breathtaking. You have the tail end of the Andes on one side and the rural beaches on the other. If you're not going there for the fishing, the landscape alone does the trip justice.
Being greeted at the lodge by the staff and guides is a great feeling as the real fun begins and you make the lodge your home for the next week. Flies are exchanged along with fishing stories as the Malbec flows all in anticipation for the first morning session. Relax and enjoy, chat with the guides, and look forward to the week ahead.
Fishing time slots
Depending on what lodge you are heading to dictates what time you’ll be heading to the river. Our sessions were perfectly timed for fishing/rest in the lodge. We would normally head out around 9am after a substantial breakfast, then fish till around 2:30pm. We would then have lunch and a siesta before heading out for the evening session: 6pm until dark.
The last hour of light really got the fish moving and we had some great action. Morning sessions and afternoon sessions can both be incredibly productive. It’s crazy to think you can catch 20lb sea trout in summer low, crystal clear water just after breakfast time on a single-handed rod, but it happens throughout the season.
Sea Trout Tackle & Set Up
If you fish for sea trout back home on your local waters, you’ll have an experienced understanding of the rods, reels and other fly fishing tackle you need to travel with, and Argentina isn’t any different. For higher water, a 7/9 switch rod comes in handy for throwing larger heavier dressed flies across to the far bank on some of the wider stretches, but most of the higher and middle stretches of the Rio Grande are similar widths to my home river the Towy in Wales.
During my recent trip I used a single-handed 10ft 7wt fly rod for 95% of my fishing time on the river. Single-handed rods make my fishing a joyful experience as the lighter the tackle in my experience, you have a lot more control over the fly and a quicker reaction time when feeling the take is essential when it comes to sea trout fishing, unlike salmon.
We went as a party of four and the three other lads were mostly keen salmon anglers, so they were fishing mainly switch rods and double handers. If that’s what you’re used to fishing that’s great, but do whatever suits you and you enjoy as it's your trip. I must admit, the first few days we had a ferocious wind like I have never fished in before. It was coming from every angle, so the heavier setups were coping with that better regarding getting the fly out, so I picked up the switch rod and joined them.
Sea Trout Flies
I was pretty concerned about getting my flies right before I was gearing up for Argentina, even after doing my due diligence online and speaking to friends that have been out there for numerous years, I still couldn’t work out exactly what these south American sea trout wanted to eat! When we started fishing, I soon realised that once again I was over overthinking it and it was mostly about getting the right depth, speed of retrieval and presentation.
Small sea trout flies and salmon doubles worked well in the low clear water conditions - the same variants as we use back home in the UK. Such as medicines, silver stoats, stoat’s tail, Peter Ross and anything with teal, silver and black in it seemed to be the most effective.
If we went through the pool swinging one of the above using various methods, such as casting square to speed the fly up and fishing deeper, we would go down the line of leeches. These are completely foreign to us. Leeches with intruder-style hooks trailing and the different colours they come in are completely crazy. We actually found that the craziest ones like chartreuse or sky baby blue worked the best! I would never have thought about fishing these in low clear water, but someone tried it years ago and it clearly works well.
Sunrays and colly dogs are also TNT, so make sure you have a good selection of sizes in your box to go. Brush up on your knots to trail your double or single hooks at the back of the fur - you’ll lose a lot less fish doing this.
Yuk bugs, nymphs & EMB’s also work well. The lodge I stayed in had their famous Aurila Prince, I very much doubt this would work on our sea trout back in Wales, but I’m excited to give it a go.
Upstream Wind - every salmon and sea trout angler’s unfavoured conditions for swinging flies. Firstly, it deforms the momentum of the line swinging the fly, so the fly essentially doesn’t fish correctly and, secondly it takes a weird effect on feeling the actual take. It's not Ideal for swinging but there is an incredible technique that is so effective on the Rio that upstream wind never ruins your day.
The indicator and a squirmy work you can fish with a sacrificial nymph if needs be, but there isn’t any point if you have a decent weighted squirmy worm on. This is an upstream casting method, and when you find the right depth with the indicator, it essentially puts the fly of choice past the fish's head, and he normally lashes out to take. I caught three double-figure sea trout in one pool in under an hour using this method on the last day.
Leader & Fluorocarbon for Sea Trout
A range from 10lbs to 19lbs works well. I fish the heavier stuff while stripping big sunrays and the lighter fishing leader material whilst nymphing. Seaguar is my preferred go-to, as it has less diameter for higher strength over most fluorocarbons.
River height and colour defines leader whilst sea trout fishing in most locations, but I personally wouldn’t advise fishing light tippet as the fish really do pull hard and paired with vicious head shakes, it won't be a great outcome with light tippet.
Technical Fishing Clothing
Just imagine spring fishing in the UK - pack fishing clothing that you would for a weekend on your river back home, and you’ll be fully prepared. The weather and conditions can change in the blink of an eye; you're either getting pounded by gale force winds wearing your windbreaker wading jacket or you’ll be lapping up the South American sun wearing just your base layer.
Chest waders are essential and only rubber boots – like many countries they don’t allow felt bottoms for obvious reasons.
What to expect to catch
We fished the first week of the season which meant that the majority of fish we were catching were chrome bars straight from the sea, some of them looked like they had been in the system for a couple of hours if that. Solid, thick, perfectly proportioned sea trout. The slightly more coloured fish of the early runners were slightly thinner but when they stayed in a pool for a certain amount of time, they got incredibly territorial, and the dog fight was insane. As the weeks go on during the season and the crocs start getting caught as the pools, I can imagine that it can be some great sport. I will definitely be heading out in April in the near future. Fishing can be hard out there, so please manage your expectations because at the end of the day, it’s still sea trout fishing.
And finally...
- Listening to the guides and learning from them is so important and will increase your catch rate. As a guide myself, I know that nothing beats local knowledge and experience of the river.
- Pack in advance but don’t over complicate it.
- Do NOT try and play these fish hard as they will snap you.
- Make sure all flies are tied on strong hooks. For tube flies only take double hooks, all trebles are banned.
- And enjoy every second from the moment you leave the house until you touch back down on home soil.
