The Mysterious Habits of Lesotho’s Rainbow Trout

The Mysterious Habits of Lesotho’s Rainbow Trout

I have some very nagging questions that I would love the answers to. They relate to the many times I have fished in Lesotho.

I have been fishing up there since the mid 90’s and it seems the more I fish there the more confused I get. Where do the trout go during a drought? Where do they go during the winter when the river levels drop? Do they die out? Do they migrate? Do they hide or hibernate? These questions would also apply to the similar but more regularly fished rivers of Rhodes and Barkley East.

I would like to share a few observations of mine over the last 20 years of fishing in Lesotho. This is a post to share some ideas, ask some questions, and hopefully  receive some feedback. I will share five “case studies” which confuse and amuse me.

Case Study 1: Sani River, April/May 2006

It was the autumn of 2006. I spent several weekends fishing the upper reaches of the Sani River, from the Pitsaneng confluence up towards where the back packers is now (about 3 km downstream of the main road). This was undoubtedly some of the best river fishing I’ve ever had. I went up twice in April and once at the end of May. Here follow my catch records:

This was a typical sight on the Sani River on the second trip. There were a good number of fish of 1 to 3 lbs cruising this pool. Clear water and lower river levels made for great sight fishing. Each pool had some fish, and some had as many as 15 good fish cruising around. On this particular day I carefully sight fished the best water and caught 6 fish of between 2 and 3 lbs. A memorable day!
A fish taken from the above pool.

6 weeks later I had a spare weekend and I went up and camped the night on the Sani River with a fishing buddy, Mike Avery. It was the 28th May. The temperature was a rediculous -13 deg at night and the river was frozen over in many places. We took a long walk down river to go and search of some fish. There was no ice on the bigger pools, and it was easy to see there were no fish present.

I could swear that there was not a fish in the river! We looked hard in every pool but found nothing. I was very disappointed as I have had two previous positive experiences fishing in winter in Lesotho. The Sani River has very little structure in the upper reaches and so it would be difficult for a fish to hide, so the mystery to me was where had the fish gone?

Johnathan Aldous who owned the Sani Top Chalet at the time had a theory that the fish migrated downstream in low river conditions. What lends weight to this theory is that I know of two very big pools lower down on the Sani River that are literally full of fish in times of low river levels, but not nearly as good during good flows. We once caught 30 fish of about 1 – 1.5 lbs in one of these big pools, in only a few hours. It was like fishing a hatchery pond. I have had similar experience on one other river during the dry season. I call these pools “hotspots”.

The migratory instinct would be very beneficial in the Sani River due to it’s lack of structure in the upper reaches. The fish would be extremely vulnerable in the upper reaches if they stayed for the winter, so migration downstream is a a possible explanation.

Case Study 2: Upper Senqu River, July 1997.

In July 1997 I hiked along the top of the Drakensberg from Mont Aux Sources to Rockeries. We were camping in Mponjwane cave at the top of the Rockeries Pass. On our rest day, we walked down to a waterfall on the Senqu River. It was an incredible sight that greeted us. There were literally fish everywhere! All in the 1 to 3lb range. The deep pools and potholes below the falls were all full of fish. There were so many that I even managed to catch one by hand that got stuck under the ice. So it’s not a true fly fishing experience, more and observation. These fish must have been trying to migrate upstream to spawn? The upper Senqu River has much better structure than the Sani River and so a downstream migratory instinct  wouldn’t be as beneficial as in the Sani River. These fish were however out and about in cold temperatures, a clearly they had a upstream migratory instinct.

Case Study 3: Upper Mokhotlong River, July 1999

My second positive winter fishing experience was in the headwaters of the Mokhotlong River. Again I was on a hike along the escarpment while still at school. It was also in July. This time I had my rod.  On one afternoon I ran off down the Mokhotlong valley to find some holding water. I only had to go a few km untill I found the first pools. Most of the river was frozen, but the pools were clear of ice. It was a really small stream up here, and only just big enough to hold fish. In half an hour of fishing I caught 1 rainbow of a pound and about 5 little brown trout of about 6″! It was easy fishing. Ever little pool that I cast into had a fish that was willing to take a fly. Back then in didn’t even know that brown trout existed up in Lesotho! Sadly I didn’t have the time to explore further downstream, but those fish were out and on the feed in the middle of winter when the water temperature was probably close to zero.

Case Study 4: Lesotho River, 2013/14 

This river won’t be named. It’s one of the few of my very special places that I won’t share. It’s a river that has a high waterfall that stops any movement of fish upstream. The top 20 km of this river near the Drakensberg escarpment has a population of trout that are essentially isolated from the rest of Lesotho’s trout population since someone stocked them up there some time ago (no idea when).

My experiences on this river lead me to believe that these trout are very territorial. I first fished the river in April 2013. The fish were very scarce. In the top 10 km of river that’s close to the Drakenbsberg escarpment, we found 11 fish. We caught 5 and saw another 6. They were all around 1.5lbs. It was very exciting sight fishing to them in this small and crystal clear stream. For a small stream it has good holding water, but was very spread out. We would sometimes walk a km between holding water. It’s pretty typical of many of the high altitude Lesotho streams. We fished for two days and on the second day we saw exactly the same fish in the same places, no surprises there.

In January the following season I hiked up to the stream again. The only access is over the Drakensberg. The amazing thing was that we seemed to find fish in EXACTLY the same places as before, except now we only caught 2 fish and saw 4. There were no fish in new places. I recall two particular fish which were a cock fish and a hen fish in the same places. I don’t have the photographic evidence to compare markings but I am convinced they were the same fish. They were now bigger than the year before but in exactly the same pools.

Why didn’t these fish move around? Maybe the fact that if they venture downstream they can’t return and this has selected for a non-migratory bloodline? In all rivers in Lesotho, the migratory instinct would be very beneficial to a trout’s survival. Maybe that’s why the population is so sparse? They are only just clinging to existence without the ability to be restocked from bigger holding water downstream.

In April 2013 I was broken off under that rock by a good fish which appeared to be a hen fish. In January 2014, Andrew Descroizilles was broken off by what I’m convinced was the exact same fish. On both occasions the fish took a dry fly as it drifted past the rock at the head of a rapid, and on both occasions the fish broke us off under the same rock.
Stalking a fish that I saw cruising the pool.
One of the pools that held a solitary fish on both occasions.
A perfect hook up after sighting the fish cruising the pool.
It’s hard to forget a fish with markings like this. I am sure that I have caught this fish twice in the same place, almost a year apart.

Case Study 5: Malibamatso River, May 2017.

My experience on the Malibamatso last week got me thinking about me writing this post. You can read my previous post about the days fishing there. It’s called “Heaven on Earth”. I thought that the river was almost devoid of fish. I had the perfect day for sighting fish. I saw one monster fish that I didn’t manage to catch. I saw one other smaller fish and one tiddler splashed at my dry fly.

I had some theories as to why the river was devoid of fish. These were all blasted out the water after the feedback to my previous blog post. Clearly it’s a commonly fished river and several people who read the post had fished there this season.

I thought the river was in beautiful condition, but all respondents remarked on how low it was. I could see that the river had risen a lot due to the recent snow so it had been lower the previous week. All the people who said they had fished there this season said it was full of fish! That blew me away! Where the hell did they go? I was fishing in perfect conditions for sighting fish and I only saw two fish.

Have they gone upstream to spawn? Had they already spawned and now gone downstream? One fish in particular appears to have been caught before. The large fish that I spent hours trying to catch. I thought it to be around 6lbs.

Alfred Röhrs, who I don’t know, read my blog and recognized the pool where I photographed the fish. He sent me a picture of his fish that he caught in exactly the same place cruising around exactly the same rock. This was sometime this season. He measured the fish at 64 cm long. That fish could be even heavier than 6lbs judging by the condition of the fish. He sent me a picture of the fish he caught. I didn’t want  overestimate it’s size but I could see how fat it was from the shadow on the bottom. Well done Alfred, that’s a fish of a life time.

The absolute hog of a fish caught by Alfred Röhrs. Unbelievable fish!
I spent hours staring into pools like this. Just watching and hoping for a fish to appear.

Where on earth have all the other fish gone since the summer? Pieter Snyders also reported that there were an almost annoying number of fish when he guided there 5 months ago. Gary Glen-Young also said he caught several fish in a short space of time a few months ago just above Oxbow lodge.

I am well aware of the trout’s ability to hide. They do this almost every day in Lesotho. You hardly ever catch a fish in Lesotho in the early morning, and you don’t see them either. They seem to miraculously appear at around 11 am and come on the feed. I don’t know if it’s a water temperature thing or feed availability?

Are the fish in the Malibamatso currently all hiding under the rocks for the winter, and was I just there on a bad day? Have they swum upstream to spawn or downstream for better holding water? I wouldn’t think there’s any need for migrating as there are plenty deep pools in this section. Was it the fact that it was such a calm and clear day that they just feel insecure about being out and on the feed? I would generally associate those habits of hiding in bright light conditions with Browns, not Rainbows.


It’s difficult to come to any general conclusion, other than it’s probably multi factorial and river dependant.

I have observed trout moving upstream to spawn in the Senqu River. They were out and about and easy to see in the 500m or so of river that I saw below the Senqu waterfall. I have caught Brown and Rainbow trout in the half frozen headwaters of the Mokhotlong River.

I have observed that the Sani River trout seem to migrate downstream in times of low flow to several “hotspot” pools. The upper reaches of the Sani probably has the least holding water of all the Lesotho rivers that I have fished and so a downstream migration would be hugely beneficial to their survival.

I have observed that the trout of the Malibamatso River near Oxbow seem to migrate either upstream or downstream at this time of year (observations made this year and in 1987 by Doug Kretzman). It’s possible they were hiding, but in water conditions such as those I encountered, Rainbow Trout are generally out and about. In almost every Lesotho trip that I have gone on, I observe that it’s almost a waste of time to fish before 10am. They clearly hide under a rock or a bank until the water warms up a bit and they start to feed. What appeared to a be a river devoid of fish, suddenly comes to life.

I have been trying to answer these questions for 20 years but I keep changing my mind. It’s one of the mysterious and unpredictable aspects of fishing in Lesotho that keeps me coming back for more.

Here follows the link to a recently written account of an adventure to fish the Malibamatso River 30 years ago. Its amazing that 30 years ago the Malibamatso Rainbows exhibited the same winter disappearing habits  as I onserved. Thanks Doug Kietzmann:

After the initial posting of this piece on my own blog, A Stream Beyond, I have chatted to several fisherman who have added there own ideas:

We all know that fish can hide from our view from quite long periods, and we also know that trout migrate. What if all fish have an upstream migratory gene, a downstream gene and a sedentary gene. Maybe the nature of each river leads to each population of trout being selected for the river.

A population of trout in river with a waterfall downstream will generally be the sedentary type or upstream type. The downstream gene will not proliferate as they can’t come back up. This is all speculation, but it definitely seems that the individual trout populations adapt to suite their home river.

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