Business: Why wait for eight months to harvest fish when you can do it at four?


As one travels along the Machakos-Kangundo Road, they can’t help but marvel at the green scenery on the farms.

It has been raining for the last two months and the region that is usually dry is greatly transformed as maize, watermelons and tomatoes, among other crops, flourish on farms.

But that is not the reason why we visited the region. Our trip takes us to Kamuthanga Fish Farm, a modern aquaculture enterprise located on the foot of Mua Hills.

Jason Hammond, the farm’s general manager, is ready to receive us. But before that, we disinfect our feet in a footbath and greet him before he starts explaining what they do and why the fish is flourishing in the semi-arid region that is not known for aquaculture.

“We breed, rear and sell fish at all stages, from fingerlings to adult tilapia. We sell about 70 tonnes of adult tilapia and thousands of fingerings annually,” he offers.

The fish is reared in a modern environment that shows how precious they are to the farm.

“This is the tank in which females lay eggs. We have a ratio of one male to three females,” says Hammond.

“The females lay eggs, the males fertilise them. Later, the workers harvest eggs from the females’ mouths and transfer them to the hatchery for hatching.”

The hatchery is located a few metres from the main fish farm, owing to the delicate nature of the fingerlings. From the unit, about 200,000 eggs are hatched monthly.

“We grow about 40,000 of the fingerings and sell the rest, mostly to small-scale farmers at an average of Sh10 each,” says Hammond.

Inside the hatchery, there are fingerlings of different ages, some of them so tiny that they look like mosquito larval.

“Fish develops in various stages, we start from eggs, then larval, fries, juvenile and adult. We grow the fingerlings in usual basins like those used for washing. However, the trick of making this technology work is in feeding and temperature control,” offers Hammond.

Temperatures are maintained at between 28-30 degrees centigrade, and the fingerlings are grouped according to their ages, and are ready for sale at one month.

Those that are not sold are transferred to a grower-out chamber, which is basically a tank that has air and water circulating unit in a technology known as Recirculating Aquaculture System.

“The filters at the middle of the tank ensure the water is cleaned of ammonia, nitrogen and carbon dioxide and has good oxygen circulation throughout. This system ensures a stress-free environment for the fish, enabling better feeding, thus stimulating growth,” says Hammond, Dutch fish expert.


The technology involves keeping fish under a roof, with lighting provided by some translucent iron sheets. This way, Hammond explains, temperatures are kept under control, meaning fish can feed throughout day and night.

“The secret of growing fish fast is in feeding, and fish feed well under high temperatures,” says Anthony Ndetto, the farm’s founder and managing director.

“Were they to be reared in ponds, fish would not feed at night as temperatures naturally drop creating a non-conducive feeding environment for the fish.”

Through the technology, he adds that temperatures at the grower-out section are maintained at between 28-30 degrees centigrade for both day and night.

“From a 300 square-metre pond, I used to harvest a tonne of fish annually, but I now harvest five times the same from a 50 square meters tank,” says Ndetto, noting the farm is 20 acres, with fish farming happening on two.

The fish is harvested at between 4-6 months under the technology, while in ponds, it is ready at eight months.

“They mature faster because of the system which allows them to feed day and night,” he says.

The average weight of tilapia fish grown in ponds at one year is 300g, but using the RAS technology, fish weighs 400-500g at four months, thus fetching better prices. According to Ndetto, after harvesting, the fish is put under fresh water without feeding for seven days before they are released to the market.

This process ensures the system is clean and the fish has no residues that could have been in feeds.

His farm is among the 24 listed to export farmed fish to the European Union, but Ndetto says he is yet to start as there is huge market locally. He sells a kilo of fish for Sh500.

The farm imports starter feeds from Egypt to supplement the ones they make with the help of FoodTechAfrica, a partnership that brings together Dutch and Kenyan companies.

Winnie Ouko, a FoodTechAfrica’s representative, says the company has already linked Kenyan and Dutch feed manufacturing companies to jointly produce fish feeds to suit all stages of growth.

Ndetto uses water from the aquaculture system for irrigation at a horticultural farm, saving him 90 per cent of fertiliser cost and reduces the use of pesticide by 67 per cent.

Margaret Gatonye, the Head of Aquaculture Projects at Larive International, says farmers should ensure they get the needed certification such as the Hazard Analysis and Critical Control Points (HACCP) to ensure food safety and expand their markets.

She advises small-scale farmers to partner with large-scale fish producers to enhance market linkages and sustainability.

First Published by The Nation


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