They have orange stripes, massive teeth and are renowned for their strength. Unlike the more famous mammal, the tigers I'm writing about are fish and they inhabit the Okavango Delta. They are renowned for their fighting ability and anglers travel from all over the world to try and catch them.

More by luck than judgement Angela and I happened to be travelling up the panhandle of the western Okavango Delta at the perfect time of year for tiger fishing. A phenomenon called the Barbel Run takes place in the Okavango in August, September and October every year that makes it marginally easier to catch tigers.

As the water levels of the Delta recede, shoals of nursery fish are forced in to the main river channels, a place fraught with danger for them. They seek refuge in the papyrus reeds only to find that predatory barbel have worked out a strategy to flush them out. For the only time in the year the barbel shoal together in their thousands and swim in to the papyrus, smashing the reeds with their bodies and tails to flush out the small fish.

Those fish that escape the cavernous mouths of the barbel face another danger, the tigerfish patrolling the edges of the reeds. It is on this border between reed and open water that your correspondent and Angela toiled, and I do mean toiled, under the African sun for 8 hours to catch tigerfish.

Our fishing guide, Otto, found the barbel nearly 2 hours downstream by fast motorboat from Drotskys Cabins, our base. The sight and noise of thousands of barbel swimming in the reeds, with hundreds of herons, egrets and cormorants in attendance is a wildlife spectacle the equal of any we've seen. It is worth the trip just to see this, but I have always wanted to catch a tigerfish and we were soon fishing.

The preferred method of catching tigers is to cast a brightly coloured lure then reel it in fast, simulating an escaping sprat. After 2 casts a minute for over 2 hours without a bite, in temperatures touching 100F and no shade (casting with a canopy above you is tricky to say the least) you begin to wonder why you are paying a ton of money to do it. Then Angela cast 2 lures and a spinner in to the reeds and lost them (£5 each replacement charge) and your enthusiasm fades further.

Then, for reasons that are often a mystery to the fishing fraternity worldwide, the fish begin to bite. Sadly we start catching barbel, a fish whose fighting skills are as legendary as those of the Italian army in World War 2. This is soon forgotten as the tigerfish begin to bite, the ferocity of the hit on the lure has you gasping for breath and shouting involuntarily. Another 4 lures are lost (£35 running total for lost tackle, it will soon cost more than hiring the boat!) as the tigerfish teeth make mincemeat of the lines!

Finally Angela lands our first tiger, a beautifully coloured, streamlined killing machine with a huge tailfin and teeth that would make a piranha envious. Much to my annoyance I lose 6 fish in a row as they jump out of the water to shake off the hook, until I finally catch my first. Otto takes a tailfin sample of each of the 9 tigerfish we eventually catch, for a DNA analysis project being run by the University of Botswana.

In between fishing we observe an 8 ft crocodile near our boat chomping it's way through the masses of barbel, a salutary reminder (along with the 4 hippo we nearly motored over on the way out) of why swimming in the Okavango is a quick way to exit the gene pool.

We return to Drotskys for sundowners at the bar, both of us chargrilled despite being covered up and liberally dosed in suntan lotion. Another fantastic day in Africa!

Ralph and Angela