Mary A. Opiyo- PhD (Fisheries Science)
- Senior Research Scientist at Kenya Marine and Fisheries Research Institute
Mary A. Opiyo
- PhD (Fisheries Science)
- Senior Research Scientist at Kenya Marine and Fisheries Research Institute
Sustainable aquaculture, Fish breeding, novel ingredients for fish feeds, Fish health management & aquatic food systems
About
82
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Introduction
I am a Senior Research Scientist in Aquaculture working on sustainable aquaculture and use of novel products in fish health management. My interest is in sustainable aquatic food systems, probiotics in aquaculture, anaesthetics in aquaculture, fish meal replacement in fish diets and enhancement of omega 3 fatty acids in farmed fish.
Current institution
Additional affiliations
April 2009 - present
Position
- Researcher
Description
- Research on fish nutrition, Aquaculture probiotics, Fish breeding and seed production, Fish health management, Aquaculture biosecurity, Integrated aquaculture, Fish anaesthesia, Integrated systems and Sustainable production of fish in low input systems.
March 2009 - August 2014
March 2009 - present
Education
May 2015 - December 2020
September 2007 - December 2010
MOI UNIVERSITY
Field of study
- AQUACULTURE
Publications
Publications (82)
Fish farmers aim to maximise fish weight relative to the feed inputs needed to turn a profit. Yet, many farmers in
Africa lack the cash flow to grow large fish and many consumers prefer, or are limited to purchasing, small fish.
This study aimed to intentionally produce small tilapia in cages by assessing the effects of higher stocking
densities an...
Duckweed (Lemna minor) have been used for several years to recover nutrients from wastewater and as feed ingredient for livestock, including fish and poultry. This study aimed at assessing the effect of different manure sources; inorganic fertilizer (a combination of DAP and Urea), and organic sources (chicken manure and cow dung manure) on the pro...
Hunger affected 278 million people in Africa in 2021, and in Kenya, the proportion of the population unable to afford a healthy diet is 81%. To combat hunger and increase resilience throughout the food system, spirulina (Arthrospira platensis) has been shown to have remarkable properties. The main aim of this study is to investigate whether protein...
A 12-week experiment was conducted to determine the effect of dietary duckweed (Lemna minor) on growth performance, body composition and fatty acid profiles of juvenile Nile tilapia (Oreochromis niloticus). Five isonitrogenous (30% crude protein) diets were prepared with the inclusion of dry ground L. minor at 0%, 5%, 10%, 15% and 20% of diet dry w...
![feed suppliers in Kenya. Adapted from [2,22].](profile/Mary-Opiyo/publication/326336121/figure/tbl2/AS:670474371612685@1536864955481/feed-suppliers-in-Kenya-Adapted-from-2-22_Q320.jpg)
Warm water aquaculture is widely practiced in Kenya and is dominated by the culture of Nile tilapia (Oreochromis niloticus) (75% of total production) followed by African catfish (Clarias gariepinus) at 18%. Aquaculture started in Kenya in 1920’s and has been on upward trend until 2014 when it peaked at 24,096 MT. However, production reduced drastic...
Fish products are essential to Kenya's economy and nutrition, yet their high perishability limits their accessibility and export potential. Developing fish value-added products-such as fish samosas, sausages, fillets, and powders-presents a promising solution, potentially enhancing resource utilization, reducing waste, and expanding markets. Despit...
Aquaponics systems integrate aquaculture and hydroponics to create a sustainable method for food production by recycling nutrients. However, nutrient waste management in aquaponics systems remains a challenge, particularly in achieving optimal growth for both fish and plants while minimizing environmental impacts. This study compared the effectiven...
Nile tilapia (Oreochromis niloticus) juveniles were fed experimental diets with duckweed (Lemna minor) supplementing fish meal at 0% (LM0), 5% (LM5), and 15% (LM15) and compared to a commercial diet as a positive control (COMM). Growth performance, feed utilization, and body composition were evaluated and compared with the control diet. The final w...
Climate-smart agriculture (CSA) has been promoted in Kenya as a panacea for climate change impacts on agricultural productivity. Consequently, various climate-smart aquaculture technologies, innovations, and management practices (CSA-TIMPs) have been developed, validated, and adopted through the Kenya Climate-Smart Agriculture Project (KCSAP). Neve...
Climate-smart agriculture (CSA) has been promoted in Kenya as a panacea for climate change impacts on agricultural productivity. Consequently, various climate-smart aquaculture technologies, innovations, and management practices (CSA-TIMPs) have been developed, validated, and adopted through the Kenya Climate-Smart Agriculture Project (KCSAP). Neve...
Aquaculture provides the much-needed high-quality protein to most of the poor people living in developing countries. The demand for fish is on the rise due to an increase in diet preferences and the declining capture fisheries, leading to the growth of aquaculture which is considered as an alternative source of food fish. The growth of the aquacult...
Aquaculture plays an important role in the provision of food, livelihood and source of income in Kenya. There is a rapid shift from extensive methods to semi-intensive and intensive culture methods with the potential to produce higher output. However, intensification in aquaculture comes with risks of diseases. In recent years, there has been an in...
Kenya is a major player in the global ornamental trade, exporting substantial quantities of ornamental fish to the global market. The sector plays an important role in the country's economy through foreign exchange. However, the country's ornamental fish industry has not fully developed to generate more economic benefits. This paper sought to ident...
Increased food demand in low and middle-income countries (LMICs) has led to the intensification of production, underpinning environmental and health hazards such as increased water needs or misuse of antimicrobials. Epidemics of diseases still emerge often, necessitating the routine administration of antimicrobials to curb their spread. Sub-therape...
Fish-farming in Kenya is challenged by the availability and high cost of feed ingredients, especially protein sources. Using black soldier fly larvae (Hermetia illucens) (BSFL) directly or indirectly as a feed ingredient to feed fish is interesting as they efficiently convert organic wastes into high-quality proteins. In addition, the freshwater sh...
In the 1980s, Artemia franciscana from San Francisco Bay (SFB) was introduced into Kenyan saltworks, where it has colonized and established stable populations. However, little is known about its biology, particularly with respect to its parental SFB population. This study compared the salinity tolerances of Kenyan (KEN) population, their SFB progen...
This study assessed knowledge in fish health, management practices and usage of prophylactic health products (PHPs) in pond and cage aquaculture systems in Kenya. Data were collected using semi-structured questionnaires in 220 fish farms randomly selected from six counties, which were previously recorded to be producing high quantities of cultured...
The effects of feeding at different densities of Artemia nauplii on the growth and survival of Macrobrachium rude larvae were explored in this study. Two experiments were carried out. In the first trial, larvae were fed three different feeding densities: 1, 3, and 5 nauplii/mL. In the second experiment, feeding densities of 5, 10, and 15 nauplii/mL...
Rainbow trout (Oncorhynchus mykiss) is among the most widely translocated fish species in the world. The current study evaluated the spawning interactions between naturalized and wild rainbow trout from two high‐altitude second‐order streams, in Kenya. Data on total length, weight, condition factor, fecundity, fertilization, egg diameter and fry su...
Utilization of quality aqua-feed relies heavily on fish meal sources of protein because of its nutritional balance. However, due to its limited supply, high cost, and decline of wild fish populations, aquaculture production has shifted focus to cheaper and more readily available alternatives to guarantee sustainable aquaculture productivity. Black...
A significant portion of the Arid and Semi-Arid Lands rural population in Kenya suffers from social challenges linked to hunger, starvation, and malnutrition. The existing hydropower dams in these areas can be leveraged upon for fish production through the adoption of cage culture. This study sought to assess the suitability and feasibility of thes...
The report is about the basics of fish health management in a fish farm
Aquaculture has been ranked as one of the fastest-growing food sub-sectors, providing quality protein to better the livelihoods of rural communities alongside curbing malnutrition and food security globally. Nonetheless, the industry’s sustainability has been threatened by the high cost of fish feeds, which account for approximately 60–70% of the t...
Sub-Saharan Africa is confronted with complex interrelated problems of affordability and accessibility to feed and food for aquaculture, livestock, poultry and pig production for the larger share of the population. Moreover, drought, flooding and increasing commodity prices are accelerating the needs for more resilient food systems and strategies s...
Rapidly increasing hatchery-raised Nile tilapia (Oreochromis niloticus) in most developing countries lack informed recommended fingerling weight for stocking in semi-intensive grow-out ponds. The current study assessed the growth performance, survival and productivity of all-male Nile tilapia fingerlings of 0.2 g, 1 g, and 5 g in an on-farm experim...
The current study assessed the diversity and abundance of phytoplankton genera in two Kenyan saltworks (Tana and Kurawa) in March and September 2021. Water samples were obtained from ponds with salinities ranging from 30 to 200 ppt by filtering 40 l of water using a 20-µm phytoplankton net. Seventy-six genera of phytoplankton were identified. Gener...
Nile tilapia (Oreochromis niloticus) is one of the most farmed fish globally, with a significant contribution improving local livelihoods, especially in developing countries. Nile tilapia was first cultured in Kenya in 1924 and is the most cultured fish species. Annually, O. niloticus accounts for 62% (∼15,000 tonnes) of total aquaculture productio...
Black soldier fly larvae (BSFL) are a potentially sustainable source of protein for use as agriculture and aquaculture feeds, and a constructive means of disposing of organic wastes. Optimizing larval culture of these larvae depends on the refinement of husbandry methods. Towards this objective we investigated the use of different substrates on lar...
This study investigated the effect of replacing soybean meal (SBM) with black soldier fly larvae meal (BSFLM) on the growth performance, feed utilization, carcass body composition, and amino ac-ids profile of Nile tilapia (Oreochromis niloticus). Three isonitrogenous (30% crude protein) diets containing BSFLM in varying proportions of 0% (BSFLM0),...
Insects have been proposed as potential alternative animal protein sources to replace fishmeal (FM), which is expensive and has limited availability for fish feed formulation. However, studies on the effects of replacing FM with black soldier fly (Hermetia illucens) larvae (BSF‐L) on growth performance of Nile tilapia (Oreochromis niloticus) fry, w...
Nile tilapia (Oreochromis niloticus) are herbivores with longer coiled intestines compared to carnivores; mouth characteristics necessary for plant shredding. Hence,
several studies have been conducted to replace feed ingredients in the diet of Nile tilapia considering the increasing cost. In this study, Water spinach (Ipomoea aquatica)
was evalua...
Aquaculture plays a major role in curbing malnutrition and food insecurity. Nonetheless, aquaculture sustainability is threatened by expensive fish feeds due to the overreliance on fish meal (FM) as the main source of protein. Fish meal is not only expensive but also scarce due to declining capture fisheries and competition from other animal feed p...
The aquaculture subsector is important in Kenya for food and nutritional security. The rapid growth of the subsector is evident especially in the widespread culture of Nile tilapia (Oreochromis niloticus); however, the gains made in the industry may be curtailed by inadequate quality seed. Currently, hatcheries are plagued by inbreeding, hybridizat...
inadequate training of personnel who can tackle fast-evolving production systems and
technologies geared towards sustainable aquaculture development has hampered the
growth of the sector. Currently, the general aquaculture training landscape in Kenya
and curricula are fragmented, do not meet labour market needs and are partially
duplicative and som...
Fish is a major source of n-3 LC-PUFA for humans. Fatty acids especially n-3 and n-6 polyunsaturated fatty acids (PUFAs) play important role in human health. This study was conducted to evaluate the effects of different inclusion levels of Ipomoea aquatica on fatty acids composition of Oreochromis niloticus fingerlings. Five diets containing 0%, 5%...
The framework aims to tackle some of the perennial challenges in the aquaculture
educational landscape including; limited knowledge, skills and innovative
capacity to operationalize and commercialize technological advancements in fish
production such as culture systems, fish breeding and genetics; fish nutrition, health
management and post-harvest...
A cross-sectional study was undertaken to examine the aquaculture extension service in Kenya. Primary data was collected using a semi-structured questionnaire administered to 292 randomly selected fish farmers and 56 extension officers in different counties in Kenya. Descriptive statistics mainly mean and frequencies were computed to determine key...
Nile tilapia (Oreochromis niloticus) culture has been faced by challenges of prolific breeding and early maturity of mixed-sex tilapia that can be solved by the culture of all-male tilapia. A study was conducted to compare the growth performance, survival and condition factor of genetically male tilapia (GMT), sex-reversed tilapia (SRT) and mixed-s...
Limited information exists on fish disease outbreaks in Kenya with most studies having been done on Nile tilapia and African catfish most of which is on parasitic diseases. However, there is a gradual shift in attention to the other disease categories with the advancement in aquaculture and the rise in commercialization and intensification. In Keny...
A study was conducted to determine the growth performance and economic viability of culturing Amur Catfish (Silurus asotus) using four different feeding regimes: Everyday feeding (EDF), Every two-days feeding (ETDF), Tertian feeding (TF) and Quartan feeding (QF) for 65 days. Twenty fingerlings of sizes between 2-3 grams each were randomly distribut...
The Eastern Africa region requires more animal protein sources to feed its growing population and combat malnutrition. Other than cattle, fish and poultry provide good sources of animal protein and yet their production is constrained by high costs of feed. The biggest barrier affecting growth of the aquaculture industry in East Africa is access to...
Development of Technologies for Improving Productivity of Aquaculture in Kenya (DTIPAK)
A 7-month experiment was carried out to determine the effects of different levels of probiotics (baker's yeast (Saccharomyces cerevisiae) and Bacillus subtilis) on Nile tilapia (Oreochromis niloticus) reared in low input ponds. Monosex male fingerlings (40 g) were randomly distributed into 28, 1.25 m³ net cages at 50 fish m⁻³ and fed twice daily at...
This study examined the market linkages and distribution channels of cultured, captured and imported fish in Kenya. A total of 113 fish traders' questionnaires and 10 key informant interviews were administered. Secondary data from published and unpublished records were used to complement primary data. Fish traders were literate enough to express th...
Nile tilapia (Oreochromis niloticus) is the most cultured fish in Kenya (80% of total production) and has mainly been cultured in ponds. In the recent past, intensive cage culture of tilapia has been emerging in Lake Victoria. Intensification may pose a challenge of environmental sustainability and disease outbreaks. Prophylactic health products (P...
Poor culture conditions in low input ponds make fish highly susceptible to infectious pathogens which lead to diseases and mortalities yet the effects of probiotics on immunity, gut microbiota and microbiological quality of fish in low input ponds are unknown. Nile tilapia, Oreochromis niloticus fingerlings (40 g) were randomly stocked at 50 fish m...
Recent rapid developments within the aquaculture sector in Kenya have necessitated increased production of quality broodstock and fish seed in the hatcheries. This study assessed the status of fish hatcheries, broodstock management and fish seed production in Kenya. Through structured questionnaires and personal interviews, data were collected from...
Three strains of African catfish (Clarias gariepinus) from the Netherlands (Dutch), Indonesia and Kenya
(Lake Victoria) were studied in hatchery conditions to compare their fecundity, growth performance and survival rates. The results indicated that fecundity was significantly higher (P < 0.05) in the Kenyan strain (145715.17 eggs Kg-1) and lower i...
Aquaculture education in Kenya needs to be brought to a higher level, both academic and vocational. Resources are limited, and fragmented curricula exist at different institutions. A proper educational framework is missing, i.e. a strategic vision that sketches what type of aquaculture education Kenya needs, and that defines its quality criteria. T...
This study was conducted to compare the growth performance and survival of three strains of
African catfish (Clarias gariepinus) cultured in Kenya. Three strains originally from the Netherlands (Dutch),
Indonesia, and Kenya, (Lake Victoria) were studied. C. gariepinus having an average initial body length of 3.87
cm and weight of 0.51 g were stocke...
Kenyan ornamental fish industry is the fastest growing ornamental industry in Africa. It includes
locally wild caught marine species and captive bred freshwater species. Presently, the industry contributes
to the economy of the country by generating income through export earning, creating employment and
enhancing livelihood of the fisher community...
This study was conducted during a fish eating campaign to determine the preference of fish
and fish value added products in Makueni County. The data is important for advising fish farmers,
traders, processors and policy makers in the aquaculture value chain. The data was obtained by randomly
administering questionnaires to respondents who were serv...
Polychlorinated biphenyls (PCBs) are classified as Persistent Organic Pollutants (POPs) regulated by the Stockholm Convention (2001). Although their production and use was stopped almost three decades ago, PCBs are environmental persistent, toxic, and bioaccumulate in biota. We assessed the levels of 7 PCB congeners (IUPAC nos. 28, 52, 101, 118, 13...
In the present study, anaesthetic effects of different sizes (5, 10, 15, 20, 25, 30, 35 and 40g) of African catfish (Clarias gariepinus) juveniles was investigated at different concentrations (0/control, 10, 15, 20, 25, 30, 35, 40, 45, 50 g/L) of sodium bicarbonate. Juveniles were bath immersed in each of the different concentrations of sodium bica...
Labeo victorianus fingerlings, post-fingerlings and brooders weighing 0.5 g, 5 g and 100 g respectively were harvested and conditioned for 24hrs before packaging for simulated transport. Fingerlings and brooders were packed in oxygen pressurized 5 L polythene bags filled with 1.5 L of water treated with 5 g of salt (NaCl) to reduce ammonia toxicity...
Nile tilapia (Oreochromis niloticus) fingerlings were reared in earthen ponds at three different feeding frequencies; twice
daily, twice after 1 day, and twice after 2 days for a period of 7 months. Three hundred and seventy five fish were stocked into each of
the nine, 150 m2 ponds with three replicates for each treatment. The fish were fed with a...
Nile tilapia (Oreochromis niloticus) fingerlings were reared in earthen ponds at three different feeding frequencies; twice daily, twice after 1 day, and twice after 2 days for a period of 7 months. Three hundred and seventy five fish were stocked into each of the nine, 150 m 2 ponds with three replicates for each treatment. The fish were fed with...
The effect of tank background colour and stocking density on growth rates and survival of Nile tilapia (Oreochromis niloticus) fry (0.32 g) were investigated. The fish were reared in aquari-um with blue, black and clear backgrounds at two stocking densities of 2 fish L-1 and 4 fish L-1. The outside walls and bottoms of each aquarium were painted to...
![Fig 2: Reported aquaculture production in Kenya (from 1950-2010) [6]](profile/Safina-Musa/publication/263441327/figure/fig1/AS:614243900592128@1523458566220/Reported-aquaculture-production-in-Kenya-from-1950-2010-6_Q320.jpg)
The profitability of commercial fish farming operation is of paramount importance to all farmers. However,
farmers must have access to well-balanced and cost effective feeds coupled with optimal on-farm feed
management practices as a prerequisite to profitable production. This paper presents an audit of the current
status of the Kenyan fish feed...
![Fig 2: Reported aquaculture production in Kenya (from 1950-2010) [6]](profile/Mary-Opiyo/publication/263660704/figure/fig1/AS:614302021062681@1523472423913/Reported-aquaculture-production-in-Kenya-from-1950-2010-6_Q320.jpg)
The profitability of commercial fish farming operation is of paramount importance to all farmers. However,
farmers must have access to well-balanced and cost effective feeds coupled with optimal on-farm feed
management practices as a prerequisite to profitable production. This paper presents an audit of the current
status of the Kenyan fish feed in...
Nile tilapia fingerlings (mean weight 0.2g, 0.5g and 5g) were packed at 35, 60, 90, 120 and 150 fish/bag for
simulated 24h transportation. Similarly, brooders (mean weight 65g) were packed at 8, 16 and 24 fish/bag.
The bags, each with a capacity of 5 L, were filled with 2 L of water and filled with pressurized oxygen. DO,
pH, temperature, total amm...
Post harvest losses in fish are one of the major challenges to food security in sub-Saharan Africa. In Kenya, consumers in rural areas consume fresh fish due to limited and/or lack of knowledge on other alternative fish products. In an effort to contribute towards addressing the issue of limited alternatives on fish value added products and deterio...
growing gap in national fish supply, as wild fish catches continue to decline. In order to balance the shortfall
between fish production and high increase in demand, the Kenyan government drafted a fiscal policy
measure in the form of Economic Stimulus Program (ESP) to stimulate economic growth in the industry.
Despite increased aquaculture adoptio...
Fish feed is the most expensive of all the operational costs in semi-intensive culture of Nile tilapia (Oreochromis niloticus) in Kenya. An experiment was conducted to compare growth and economic returns of O. niloticus reared on feeds from commercial companies and on farm made fish feeds in Kenya. Two commercial feeds, Uga feed (diet 1), Crop king...
Kenya has a great potential for aquaculture growth by producing additional volumes of fish to fill the
growing gap in national fish supply, as wild fish catches continue to decline. In order to balance the shortfall
between fish production and high increase in demand, the Kenyan government drafted a fiscal policy
measure in the form of Economic Sti...
Fish feed constitute s 40- 60% of the total operational costs of a fish farm. Commercial feeds are often too expensive for rural fish farmers. Consequently , farmers use non - conventional and locally available fish feed ingredients including agro -industrial by - pro ducts . These feeds have not led to increased pond productivity due to poor proce...
The effectiveness of sodium bicarbonate as an anaesthetic for Nile tilapia (Oreochromis
niloticus) juveniles ranging from 2 to 27g was investigated. The juveniles were exposed to different concentrations of 0 (control), 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 g/L of sodium bicarbonate solution. Fish were bath immersed in each of the different conc...
The effects of replacing fish meal with Caridina nilotica as a protein ingredient on growth performance, nutrient utilization, carcass, proximate composition and economic benefits in Nile tilapia (Oreochromis niloticus) culture was evaluated. Replacement of the FM with C. nilotica was done at 25%, 50%, 75% and 100% (D25, D50, D75 and D100) and the...
The Gastropod Melanoides tuberculatus plays a sig-nificant role in hampering fish larval production in earthen ponds. This study investigated use of tobacco waste to assess behavioural and survival responses of M. tuberculatus at different concentra-tions of tobacco waste solution of 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2 g L À1 . Mean escape...
There is considerable variability in aquaculture production within the study areas of Gucha, Meru and Taita/Taveta regions. Aquaculture activities involve the production of Nile tilapia and African catfish using earthen ponds. Most ponds are individually owned (93.8%). Most of the ponds were constructed and stocked between January 2007 and July 201...
Commonly utilized feed ingredients for culture of Nile tilapia (Oreochromis niloticus) and
African catfish (Clarias gariepinus) from Kenya, Tanzania and Rwanda were collected over
a period of six months (January - June 2010) and evaluated for their nutritive composition
through proximate analysis. Most of the fish feed ingredients were found in a...
The GastropodMelanoides tuberculatusplays a significant role in hampering fish larval production
in earthen ponds. This study investigated use of
tobacco waste to assess behavioural and survival
responses of M. tuberculatusat different concentrations of tobacco waste solution of 0.25, 0.5, 0.75,
1.0, 1.25, 1.5, 1.75 and 2 g L
�1
. Mean escape
time...
Commonly utilized feed ingredients for culture of Nile tilapia (Oreochromis niloticus) and Africa catfish (Clarias gariepinus) mainly from agricultural by-products were sampled in Kenya, Tanzania and Rwanda. Proximate analysis was performed on 30 samples of both animal and plant origin to test the potential nutritive value for O. niloticus and C. g...
Aquaculture production in Kenya is still low compared to the other sub-sectors of the fishery industry. It Contribted 0.7% of total fish production in 2005 compared to 0.5% in 2000. It is therefore , apparent that aquaculture has never taken off in the country and lack of information on profitability of fish farming could be one reason among other...
Questions
Question (1)
The call for papers is open for article collection on Advancements in Alternative Proteins for Aquafeed: Enhancing Nutritional Quality and Utilization
The Collection is being hosted by the Taylor & Francis journal Cogent Food & Agriculture (Impact Factor 2.0 (2022)
Focus areas are on:
* Investigating the supplementation of agents like exogenous enzymes, prebiotics, and probiotics, either individually or in combination, to enhance nutrient utilization, growth, and overall health of fish fed plant or insect-based diets
* Exploring diverse physical, chemical, and biological methods for improving the nutrient quality and utilization of alternative protein sources in aquafeed
*Enhancing the nutritional quality and utilization of insects as protein sources in aquafeed, including feeding different substrates
* Supplementing limited essential amino acids and conditionally essential amino acids to alternative protein sources in aquafeed.
Please contact Marya Baig at marya.baig@tandf.co.uk with any queries and discount codes regarding this Article Collection. Deadline is 30th July 2024
