With circular cages, we keep over 200,000 fish

The water rises up and down creating beautiful waves as the wind blows soothingly from the lake.

Standing on the shores of Lake Victoria at Ramba Beach on Mfangano Island, Homa Bay County, one appreciates the beautiful work of nature.

It is on this magnificent beach that a family has taken cage fish rearing to a new level.

Jutting out of the waters are two circular cages, which Thomas Wafula, the cage manager at Lake View Fisheries Ltd that owns them, says are made from High-Density Polyethylene (HDPE) material in a technology mostly applied in mariculture.

Wafula is dressed in a black wetsuit, a mask and a scuba tank ready to begin work on inspecting the cages.

After a 10-minute motorboat ride, he reaches the two cages.

Soon, he plunges inside the waters of one of the cages and after about five minutes, he re-emerges showing a thumb sign, an indication that all is fine.

“I do this every day in both cages to inspect them, feed the fish and check on how they are doing. We feed the fish three times a day, at 9am, 2pm and 5pm,” says Wafula, noting that besides the circular cages, the farm also has a tilapia hatchery, two metal cages and 31 ponds.

With a capacity of 25 tonnes, the circular cages that are covered with a green net, have a diameter of 20 metres and depth of 6 metres.

“Each cage has four nets in total. One that holds the fish, another that keeps water predators at bay, the third one holds feeds so that they do not spill out while finally the outer one covers the cage, preventing predators like birds,” explains Wafula.

The farm keeps a total of about 200,000 fish in the cages, half of the figure in each.

“We start by hatching the fingerlings using the re-circulation technology from a breeding stock of 2,000 tilapia that produce over 100,000 mono-sex fingerlings in a month,” says Dr Gilbert Mbeo, 34, one of the directors of Lake View Fisheries, noting they sell the fingerlings to farmers from Sh5 to Sh10, depending on the size.

BIG CAPACITY
Ronald Cruz, an aquaculture expert and the farm manager, says they collect the tilapia breeding stock from various fish farms in the region and from the lake.

“Once the fries are about a month old, we transfer them to the nursery where we feed them with mash and small pellets for two months until they reach 5g. We then transfer them to the circular and metal cages.”

He notes the circular cages have large capacity compared to square ones. “The HDPE cages can withstand strong ocean or lake waves that often damage such structures,” he offers.

The farm stocked the circular cages, which cost about Sh1 million each and were erected in the lake in February, with mono-sex tilapia fingerlings in April and they expect to harvest in September at 400g when they would have matured.

According to Cruz, they mainly feed the fish on floating pellets which they import from Israel due to low quality feeds in the market, making them mature at six months, instead of eight.

They have been harvesting from earthen ponds and the other two square cages measuring 4m by 4m, with a stock density of 7,000 fish each.

“We sell the fish at Sh300 per kilo. On the other hand, processed fish from which intestines and scales have been removed, goes for Sh600 a kilo,” offers Dr Mbeo, adding they sell the fish to hotels and traders in Mbita, Kisumu, Kakamega and Nairobi.

They harvest using hand nets that are cast inside the cages and ponds, an exercise that is normally done very early in the morning when the fish are mobile.

“Our first harvest from the two square cages was in February where we got 10,000 tilapia fish,” says Cruz, noting they plan to increase the total number of cages to 52 with targeting production capacity of 10,000 tonnes of fish in the next five years.

PIONEER AQUACULTURE ENTERPRISE

Lake View, according to Dr Mbeo who works as a neurologist in the US, but was recently in the country on holiday, spends Sh500,000 on feeds per month both for the hatchery and cages.

“We use approximately 250 and 400 20kg bags in the hatchery and cages respectively.”

Dr Mbeo says he and his sister started the agribusiness in 2013 on small-scale out of passion for fish, and have managed to turn it into a pioneer commercial aquaculture enterprise using latest technology.

“We visited Mfangano Island, our ancestral home, sometimes in 2010 and went back to the US with several ideas to pursue. My brother, Gilbert, has always been passionate about fish farming,” chips in Michelle Mbeo, the co-director, who works at an information technology firm in the US.

Through research, the siblings have learned a lot about pond and cage fish farming.
“We realised that in a small area in the lake, we can keep a large number fish using the cages compared to the ponds,” says Michelle, 35, adding they have 31 employees and they do a lot of video-conferencing to know what is happening on the farm.

Their efforts are paying off as the company was recently ranked third under the Small and Medium-Size Enterprise category during the Green Innovation Awards by National Environment Trust Fund, a state corporation charged with spurring sustainable development. She admits that keeping fish in cages is an expensive venture.

DWINDLING STOCK
“We started the fish venture with a capital of about Sh100,000, then mainly keeping fish in ponds. We then brought in our parents and pumped in more cash from our savings to go into cage farming,” says Michelle, noting expensive feeds are one of their biggest challenges.

They later injected more money that went into getting right licences and permits from National Environment and Management Agency, community sensitisation, construction of a hatchery, more fish ponds, administration block, training staff and buying necessary machinery and feeds.

Dr Tsuma Jembe, a senior Research Scientist at Kenya Marine and Fisheries Research Institute, says cages curb over-fishing rampant in the lake, which has led to dwindling tilapia stocks.

“When using cages, one should watch the depth of the water, circulation of water currents, temperatures, and oxygen level to enable fish to breathe. Watch for the maritime routes. That way you don’t block vessels,” he explains, noting farmers need licences and permits to practice cage fish farming.

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Other side
Diseases to watch out for

• Bacterial tail and fin rot are common diseases which attack fish reared in both ponds and under the cage system.
• Fin rot is associated with polluted and unsanitary conditions in hatcheries.

• Though bacteria are the causative agent of tail and fin rot, pathogenic protozoans and fungi may be involved.