It was my elder brother, Ken, who taught me how to fish for brown trout in the burns around Balquidder where we often camped in a bothy under the lee of Ben Ledi. The trout, pink-fleshed, were rolled in oatmeal and fried. The surplus were given to the shepherd, a spare, taciturn man, who must have walked for 20 miles over the hills every day with his dogs, keeping an eye on the sheep.

One spring, my father showed me the salmon swimming almost vertically up the falls near Boat of Garten – you begin to believe in miracles after sights like that – in contrast to the shoals of mackerel at our summer holiday cottage on the Arisaig peninsula which were caught in bucketfuls using limpets as bait.

Africa is a little different. Our fish are dried whole in the sun or smoked over a slow-burning wood fire. Having been flattened, they can be packed snugly in suitcases when travelling and given to friends and family who appreciate the finer tastes of life, although airport customs officials may require some background detail on their origins.

Talapia is the commonest fresh fish, steamed in banana leaves or deep-fried, with a stiff cassava or maize porridge and a vivid crimson dollop of fresh homemade chilli relish on the side. Whiskered catfish are available in many village markets or strung on a line by the roadside, and can be very big.

We suspect there is one in the muddy pool at the bottom of the farm as our son was pulled off balance and the line jerked out of his hand as we were standing talking one afternoon. If he succeeds and catches it, I will pass if offered a taste – catfish are bottom feeders and people often drown in East and southern Africa without the body ever being found.

The last time I caught a fish was in a clear pool in the Malalotja game reserve in Swaziland, a huge stretch of wilds and high mountains where we were spending Christmas. I was showing my daughter how to cast with a red-bandied earthworm as bait. There being no sign of action, she wandered off upstream. Then came a tug and the battered old rod bent. After a few minutes, a surprisingly large trout was landed on the grass bank. We returned to the camp in triumph, bearing what was to be the unexpected and delicious fish course.

Shellfish are one of the joys of living here. Working not far from Maputo some years ago, fresh prawns were often presented for inspection at our clinic by the hawker. They were still twitching. After grilling over a charcoal barbecue, nothing was spared, neither sweetish flesh nor crunchable carapace. When we were down on the Wild Coast at Port St Johns in South Africa for holidays, the fishermen’s families would negotiate with us about the price of small lobsters or crayfish, then dig a shallow pit in the beach sand where the live beauties stayed while we swam, later meeting their fate as the sun went down.

On the Indian Ocean’s beaches at Inhaca Island or Durban, I now know why you’ll find women bent double, digging with a thin short stick and never ceasing to chatter with satisfaction; they are looking for the speck of a blowhole under which a small clam will lurk, and the growing pile in their grass baskets will make a tasty chowder.

I owe a very personal debt to fish. About 30 years ago, on a sodden, misty December afternoon with a chill wind whipping off the Mersey, I was trying to persuade the girl I loved to join me in Swaziland. Fish from the Nile had been an important part of her childhood in the Sudan, and the main reason she survived practising as a lawyer in Liverpool was that Birkenhead Market had first-class fishmongers where ‘wetfish’ were laid out on white marble slabs.

“ Are there fresh fish in Swaziland?”

“ Ah – um – “

This presented a major obstacle, the Kingdom of Swaziland being landlocked.

“ – uh – well , yes, there are, actually.”

What I threw on the scales at that crucial moment were the tilapia rumoured to be available at a fish farm on a small dam far out in the bush near Simunye sugar estate. Fortunately the rumour turned out to be true but at that instant, my dear girl’s choice was either me – or a mullet.

Dr David Vost studied medicine at Glasgow University and is currently working at a hospital in Swaziland. He and his family live on a small farm in Northern Uganda near the Albert Nile. davidvostsz@gmail.com