Researchers perfect fingerling breeding in Kenya

In the last 10 years, aquaculture has become a popular venture for farmers across the country seeking to diversify their revenue streams.

For most farmers, setting up a pond for their aquaculture business is just the beginning. Identifying the species of fish and sourcing quality fingerlings is one of the most daunting tasks for both beginners and seasoned fish farmers.

Concerns about high mortality rates, low-quality hatchlings, and even buying tadpoles instead of fish are some of the fears farmers face as they search for fingerlings.

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The main source of fish fingerlings in the country is the Kenya Marine and Fisheries Research Institute (KMFRI) in Sagana Centre in Kirinyaga County.

It currently hosts a state-of-the-art fingerling production unit (Hatchery) and is the gene bank for the most preferred aquaculture species of tilapia and catfish in the country.

KMFRI Sagana Centre Director Dr Domitila Kyule-Muendo, who is also a senior research scientist, explained that the facility is the headquarters for aquaculture research and training stations in the country. 

She explained that the facility conducts research, produces high-quality fingerlings, and offers training to farmers and government officers on the best practices for aquaculture production.

Dr Muendo said that one of the biggest concerns for the aquaculture sector was access to quality hatchlings for tilapia, catfish, Nile perch, and other species popular in the aquaculture sector.

“We are addressing the challenges of quality fingerlings. When farmers complain of stunted growth or high mortality rates, we conduct research and find a solution,” she said.

The facility also sells brooders and works with over 80 authenticated fish hatcheries across the country.

“We are the first tier in fingerling production, and we supply the other private hatcheries and multiplier stations in the country,” she said.

She noted that the demand for quality fingerlings is very high as farmers from Central Kenya embrace aquaculture, and their counterparts in Western Kenya and Lake Victoria regions make orders the hatchlings. The process of growing and maintaining high-quality brooders, harvesting eggs from both catfish and tilapia, researching fish species, and disseminating information to farmers on the best practices for aquaculture is part of the KMFRI mandate.

“We have received assistance from the Aquaculture Business Development Program (ABDP) to boost mass production for hatchlings and training to fisheries extension officers in counties,” she said.

ABDP is a program jointly funded by the National Government and the International Fund for Agricultural Development (IFAD).

In hatchling production, KMFRI has been improving the stocks of tilapia and catfish in the country through research.

“We are currently in generation 8 of tilapia, which is a fast-growing strain of the species and which is lucrative for farmers,” she explained.

Delving into the process of producing high-quality fingerlings, KMFRI Research Scientist Dr Jacob Abwao explained that the reason farmers in Kenya prefer tilapia and catfish is their high productivity in terms of size and the time it takes to reach maturity.

“Farmers’ profit margins are higher for tilapia and catfish compared to other species, which is why they are preferred for aquaculture,” Dr. Abwao said. To produce Tilapia mono-sex fingerlings, the process kicks off with the harvesting of females, which should be caught gently in a deep net, and the eggs of mouth-brooders gently squeezed from the ovary into a container. This is done by hand, with each fish stripped and then returned to the holding tank. 

Once the eggs are collected, they are moved to the incubator until they hatch into fry.

The key components for hatchling production are meticulous control of temperature, water quality, and feeds. In the case of catfish, producing hatchlings is a necessity as they do not reproduce or mate effectively in captivity.

Female broodfish can be induced to reproduce artificially every 4–6 weeks without affecting either the quality or quantity of eggs obtained after stripping.

They are injected with reproductive hormones 6-12 hours before stripping to stimulate egg production. Once they are ready for stripping, one or two male catfish are identified and dissected for the procurement of milt (sperm).

The eggs and milt are mixed in a saline solution and are then deposited in an incubation unit awaiting fertilisation and hatching.

One challenge facing catfish farming is cannibalism, which affects the productivity of the species.

“Sometimes hatcheries provide farmers with very small fingerlings, and young catfish need high quantities of live feed such as algae, zooplankton, and artemia. If these are not provided, they eat the weaker ones,” Dr Abwao said.

One of the ways KMFRI is addressing this issue is by improving the breeds of tilapia and catfish through research and selective breeding.

“We consider the growth rate of the fish and select the fast-growing individual fish to be the parents of the next generations. That is how we are now in Generation 8 of tilapia,” Dr Abwao said. Dr Abwao also noted another consideration is the survival rate. For instance, through breeding, they can nurture fast-growing fish that mature in four months compared to six months.

One of the most significant advancements in the selective breeding process is the development of an African catfish cross-bred from Indonesian and Dutch strains of catfish. According to the Lead Research Scientist in the catfish cross-breeding project, Dr. Mary Opiyo, they had several studies on the cross between the Kenyan, Dutch, and Indonesian catfish strains and produced a hybrid that had fast growth and low cannibalism due to reduced aggression.

“Although when we cross-bred the Kenyan and Dutch catfish strains, the output of eggs was high, but survival rates were low,” Dr. Opiyo stated.