Floating fish ponds come in handy for small plots

Friday July 31 2015
fish px

James Mwaniki filling one of his fish ponds with water in his greenhouse in Runyenjes Town, Embu. PHOTO | ALEX NYAGA |


James Mwaniki is busy cleaning fish ponds in his greenhouse in Runyenjes Town. However, these are not your usual fish ponds dug out in the ground. These ones are made of wood and polythene papers, and are raised a few feet from the ground.

His fish farming journey started early last year. However, Mwaniki encountered a unique challenge that got him thinking. He says most of the fish died due to cold weather. But that was not the only problem, he had predators, including birds and dogs to deal with. The ordinary fish ponds also took a lot of space.

Mwaniki, who holds a diploma in Mechanical Engineering from the Railways Training Institute in Nairobi, says he went to the internet and started researching.

“I started researching on the best practices in fish farming. I discovered one can actually rare fish in raised ponds which does not take a lot of space and quickly tried it out. It is working,” he adds.

He says the ponds hold more fish than the ones dug up in the ground. They also make it easier to harvest.

“The fact that the ponds are also kept in the greenhouse also means predators are kept at bay,” the 39-year-old father of two told us when we visited his farm this week.


The polythene liner holds the water while the wooden material insulates the fish against extreme cold.

Mwaniki started with one pond and later added three and a hatchery where he develops the fingerlings. He is currently rearing hundreds of fish in an 1/8 acre piece of land.

His fish ponds are stocked with mature catfish ready for harvesting. With a single pond carrying 2,000 catfish fingerlings, he looks forward to making good money. 

Last time he harvested 1,200 fish each weighing up to 1.5kgs. With 1,800 kilogrammes of fish per pond, and with a kilo of fish going for Sh300, he made a cool Sh540,000.

His main markets are hotels in Nairobi, Thika and Nakuru. “My interest in fish farming started when I was still a boy. My father grew coffee, tea and kept cows but he would time and again buy fish for us. As I grew up, I thought I could rear fish,” says Mwaniki who also runs his own ICT company, Prime Career Networks Ltd, which he formed in 2011.

“This dream has always been there only that I did not have capital and land to sink the fish ponds.”


Mwaniki says increased subdivision of land, arising out of population growth, has made the traditional rearing of fish almost impossible as the normal fish ponds require a lot of space. Put other domestic animals into the mix and you are left with no space at all. “That is why I had to rent a small plot to make the first fish pond,” says Mwaniki.

He used his savings of Sh150,000 as to build the wooden framework which was enough to accommodate 2,000 catfishes. “The wood is locally available, same to the paper which costs Sh200 a meter,” he says.

The pond is connected to inlet and outlet pipes using a pump to ensure the water is always fresh and clean. This kind of fish pond can last up to six years depending on how best it is taken care of, says Catherine Rutere, an agricultural extension officer from the Department of Fisheries.

He uses a net to remove solid waste from the water that is drained before it is pumped into the cleansing tank just outside the greenhouse. This ensures water conservation as water is recycled throughout.

The farmer uses some of the nutrients-rich water from the fishponds to grow seedlings in his compound.  “I also use water from the ponds for irrigation to ensure there is no wastage. This guarantees maximum utilisation of resources,” he adds.

The fact that he is able to regulate the temperature in the green house makes fish to grow faster.

Catherine terms the technology new and unique, saying anyone wishing to venture into fish farming should consider it. She says they are encouraging farmers to embrace the technology which has since been named ‘Raised Aquacultural System’.

Greenhouses also help Mwaniki to maintain hygiene in the ponds. “A clean environment is critical for fish farming to avoid contamination during harvesting. It is also good for the overall growth of fish,” he explains.


Mwaniki has also built a hatchery in his greenhouse where he produced catfish fingerlings.  He stocks the ponds with fingerlings once they measure three to four inches.

The hatchery is a simple facility that uses flow-through ponds made of wooden frameworks with a liner that holds around 90 gallons of water for egg incubation and fingerling rearing.  “The hatchery requires supply of clean water. Incubation time is approximately 5-7 days, depending on water temperature,” he says. 

The fly-fingerings are then kept in the hatchery for another 10 days before they are transferred to nursery pond in readiness for stocking. 

One of the challenges Mwaniki is facing is fact that bigger fish eat the small ones at times. “To minimise the cannibalism, I sort them out according to sizes after the first two weeks of stocking.”

Mwaniki says he wants to cast his net even wider to catch customers as demand for fish grows. Mwaniki also sells fingerlings to other farmers for between Sh10 and Sh20 each.

The business is doing well and has seen Mwaniki buy a car which he uses to supply the fish. “I have also bought a piece of land where I want to increase the ponds to 10 by the end of this year,” he says.