The status and challenges of aquaculture development in Dodoma, a semi-arid region in Tanzania

Demand for fish is growing rapidly in Tanzania due to population growth and rising incomes. However, as fewer wild fish are being caught, there is a gap in fish supply. Aquaculture is a viable alternative source to meet the gap in fish demand. Tanzania has the perfect climate and land for fish farming. Aquaculture in fresh and salt water has grown quickly, yet the potential is not being fully tapped. Thus, the study assessed the growth of aquaculture in Dodoma, a rapidly developing semi-arid region of Tanzania, in order to determine its potential, challenges, and solutions. Thirty-six fish farmers from Dodoma urban district were visited and interviewed. The interviews gathered information about management practices, fish yield, and challenges. The findings show that aquaculture in the region began around 9 years ago, when the region began to expand. The aquaculture includes small-scale pond farming of Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus). Fish yield was about 1925 kg ha−1 per culture cycle, and fish customers are definitely available. The main challenges were limited supply and high prices of fish feed and seeds, and limited water supply. Use of commercial feed, pond fertilisation, access to extension services, and ownership of a borehole were related to high fish yields in both species. Expansion of aquaculture in the region is possible with the improvement of extension services and training of farmers in proper breeding, feeding, and water management. To decrease water demands, integrated aquaculture, water recycling, and aquaponics should be encouraged.


Introduction
Aquaculture plays a vital role in providing affordable and high-quality protein throughout the world (Subasinghe et al. 2009;Pradeepkiran 2019;Gephart et al. 2020). Fish protein has a high nutritional value due to its well-balanced nutrients (Tacon et al. 2020). However, fish supply from the wild catch has decreased, creating a fish demand deficit (Naylor et al. 2021). Aquaculture is a promising alternative fish source for meeting demand while reducing pressure on wild fish stocks Tran et al. 2019). Globally, aquaculture production has increased rapidly during the past 50 years due to technological advancements (Subasinghe et al. 2009;Naylor et al. 2021). The growth rate of aquaculture, however, differs across different continents. Asia is the world's largest aquaculture producer, accounting for about 92% of the live-weight volume of aquatic animals and seaweed (Naylor et al. 2021).
In Africa, aquaculture production has grown by 11% annually on average during the past 20 years due to private sector investments Ragasa et al. 2022). The highest production levels are found in North Africa, particularly in Egypt Adeleke et al. 2020;Kaleem and Sabi 2021). However, the contribution of African aquaculture to world aquaculture production is still low, at about 2.7% of live weight annually Adeleke et al. 2020). The reasons for the slow development of aquaculture in Africa include a lack of infrastructure and capital, limited technological know-how, and poor governance Hinrichsen et al. 2022). Small-scale fish farmers are indeed the major producer group in Africa (Machena and Moehl 2000;Ragasa et al. 2022).
Tanzania has great potential for aquaculture development (Rukanda and Sigurgeirsson 2018;Berg et al. 2021). The climate and land are ideal for fish farming, and the demand for fish is rising rapidly due to population growth and growing incomes (Mosha and Daudi 2020;Berg et al. 2021). In addition, Tanzania has experienced a decline in wild fish catches due to climatic changes, environmental degradation, overfishing, and illegal fishing (Rukanda and Sigurgeirsson 2018). As a result, aquaculture development is critical to supplementing wild catches. Aquaculture in Tanzania started in the form of sport fishing in 1927, when rainbow trout (Onchorynchus mykiss) from Scotland were introduced into streams around Mount Kilimanjaro and in the Mbeya region (Rukanda and Sigurgeirsson 2018;Mzula et al. 2021). This was followed by the experimental culture of tilapia in the Tanga and Mwanza regions (Rukanda and Sigurgeirsson 2018;van der Heijden et al. 2018). A keen interest in aquaculture developed after independence in 1961, when the government and non-government organisations assisted the communities through the provision of fingerlings and technical and financial assistance (Rukanda and Sigurgeirsson 2018). Since then, inland aquaculture of Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) has increased substantially (Rukanda and Sigurgeirsson 2018). The number of freshwater ponds in mainland Tanzania is estimated to be more than 20,000.
Fish farming is largely practised in the Ruvuma, Iringa, and Mbeya regions in the southern highlands and the Kilimanjaro region in the northern part of the country (Rukanda and Sigurgeirsson 2018;Mzula et al. 2021). Nile tilapia is the dominant farmed fish, making up more than 90% of total aquaculture production in the country (Peart et al. 2021). However, fish farming is still primarily a small-scale activity, where farmers own small fish farms with one or a few small ponds ranging in size from 150 to 300 m 2 (Kaliba et al. 2006;Mzula et al. 2021). Aquaculture contributes only about 4% of total fish production in the country (Peart et al. 2021). This amount is low compared to the global level, where aquaculture contributes about 46% of total fish production (Subasinghe et al. 2009;Peart et al. 2021). The low production of fish raises prices, making it less affordable for lowincome households.
Some of the factors limiting aquaculture expansion are a lack of capital and financial opportunities, the scarcity and high price of commercial feeds and fingerlings (fish seed), and a lack of knowledge among farmers about improved aquaculture practises (Rukanda and Sigurgeirsson 2018;Mzula et al. 2021). The high prices of commercial feeds force small-scale farmers to use alternative sources of feeds such as domestic leftovers, maize bran, wheat bran, vegetables, and wild grass as fish feeds (Madalla 2008;van der Heijden et al. 2018;Mmanda et al. 2020). Small-scale aquaculture is normally integrated with other agricultural activities such as gardening and animal production on small pieces of land (Ogello et al. 2013). The animals kept ensure the availability of manure, which is used as the main source of fertiliser for the fish ponds (Ogello et al. 2013;Chenyambuga et al. 2014). Another issue facing aquaculture in Tanzania is the supply and quality of fingerlings (Kajungiro et al. 2019). There are a small number of operating hatcheries, and they use a low level of technology in larval rearing (Rukanda and Sigurgeirsson 2018;Kajungiro et al. 2019). The limited availability of fingerlings and high prices force some fish farmers to obtain seeds from wild capture, mainly from rivers (van der Heijden et al. 2018). In addition, well-established extension services are important in order to disseminate knowledge to fish farmers on proper feeding, good pond management practices, and maintenance of fish health (van der Heijden et al. 2018;Wanja et al. 2020;Mzula et al. 2021). Limited extension services are associated with poor performance and outbreaks of fish diseases (Mzula et al. 2021).
Fish farming in the central zone of Tanzania, mainly the Dodoma and Singida regions, is low, partly due to the semi-arid conditions that result in a shortage of water (Bwathondi 2002;Berg et al. 2021). Lack of awareness and motivation within the community about the economic potential of fish farming also hinders aquaculture development in these regions. However, the Dodoma region has expanded rapidly in recent years due to the establishment of the University of Dodoma and the shift of government headquarters from Dar es Salaam to the region (Msongaleli et al. 2022). The growth of the human population has increased the demand for food, especially animal protein. This creates an opportunity for aquaculture development for income generation. However, there are no studies on the status of aquaculture development in the region. Thus, the aim of the study was to fill this gap. Specifically, we wanted to answer the following questions: (1) What is the current status of aquaculture development in the Dodoma region? (2) What are the constraints for aquaculture development in the region? (3) How do management practises influence fish yield?

Study area
The study was conducted in the Dodoma region in central Tanzania. The region is defined by latitudes 4 to 8° south and longitudes 35 to 37° east (Turner et al. 2019). The region hosts one of the largest universities in Tanzania, the University of Dodoma. According to the 2012 national census, the region had a population of 2,083,588 (Tanzania URT 2013). The population has increased rapidly because the government headquarters were relocated from Dar es Salaam to this region.

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The climate of the region is mostly semi-arid due to low and erratic rains. It has a single rainy season that lasts from November/December to March/April. Total annual rainfall ranges from 500 to 800 mm, with significant geographical, seasonal, and annual variation (Shemsanga et al. 2017). Temperature differences between day and night can be significant, with hot afternoons reaching 35°C and chilly nights reaching 10°C (Shemsanga et al. 2017). Temperature differences are observed between day and night and may be very high, with hot afternoons going up to 35°C and chilly nights going down to 10°C (Shemsanga et al. 2017).
Crop production and livestock farming are the major economic activities in the Dodoma region. Draught-tolerant crops such as sorghum, millet, maize, and sunflower are grown for food, while grapes are grown as a cash crop (Tanzania URT 2006). Aquaculture development in the region is not well documented. According to a household survey conducted in 2002 (Tanzania URT 2006), small-scale fish farming was practised only in the Mpwapwa district. Hombolo Dam, located in the Dodoma urban district, supports fishing activities and supplies water for irrigation and domestic use (Turner et al. 2019;Gayo 2021). However, fish stocks in the dam have decreased dramatically due to overfishing and poor management (Gayo 2021).

Data collection
Data was collected from seven wards in the Dodoma urban district ( Fig. 1) in May 2021. Out of the seven districts in the region, the Dodoma urban district was chosen for this study because of its rapid growth (Msongaleli et al. 2022). Additionally, the Dodoma Urban Water Supply (DUWASA) provides water supply services to the majority of the district, expanding the prospects for aquaculture (Msongaleli et al. 2022). The majority of the other districts do not have reliable sources of water (Shemsanga et al. 2018). The data was collected through field visits and interviews with fish farmers. The district fisheries officer provided information on the number and location of fish growers in the district. Structured questionnaires were used to gather information from the pond owners on the availability of inputs, services, and management practices. The questionnaires specifically gathered data on the age of the farm/pond, the availability and cost of feed and fingerlings, extension services, the supply of water, the species of fish cultured, the amount of fish produced during the previous culture cycle, and fish marketing. The questionnaire also collected data on pond size, type, stocking density, challenges, and potential solutions. The interviews were conducted in private and in comfortable environments.

Data analysis
Histograms, box plots, and scatter diagrams were used to visualise the data. Chi-square tests were used to compare the distribution of categorical data between independent groups. Welch's t-test was used to compare the price of fingerlings, the selling price of harvested fish, and fish yield among the fish species farmed. Fish yield per culture cycle was calculated as the amount of fish harvested (kg) over a pond area (m 2 ). The values were then used to estimate the fish yield per hectare per culture cycle. Generalised additive models (GAM) were used to determine the associations between fish yield and the explanatory variables. GAM is a semi-parametric model that uses smooth functions to fit response variables to explanatory variables. In this case, stocking density and pond age formed the nonparametric component of the model, while pond fertilisation, feed source, water source, pond type, and accessibility to extension services formed the parametric component. We ran multivariate models with all the predictor variables. The models were evaluated by using the gam.check() function to check for multicollinearity between the predictor variables and the concurvity() function to check for concurvity of the models. A p-value of 0.05 was used as the level of significance. All the analyses were done in R version 4.2.0.

Results
The district had 36 fish farms, all of which were visited. About 77.4% of the farms were owned by a single farmer, while 22.6% were owned by a group of farmers. The total number of ponds was 75, averaging about 2 ± 0.8 SD ponds per farm. The species cultured were Nile tilapia and African catfish. Tilapia ponds were 55, while catfish ponds were 20. The pond size ranged from 70 to 600 m 2 , with an average size of 180 m 2 . The oldest fish farm was established 9 years ago, while most of the other farms were new, averaging 3.5 years ± 1.4 SD. The farmers purchased fingerlings from hatcheries in the Dar es Salaam and Morogoro regions (43%), nearby farms (51%), and the wild (6%). Prices of fingerlings range from 0.05 to 0.17 USD per fingerling (Fig. 1a). The mean price of catfish fingerlings was USD 0.13 ± 0.03 SD per fingerling, while that of tilapia fingerlings was USD 0.1 ± 0.02 SD per fingerling. The price differences between the species were statistically significant (t = 3.221, p = 0.004).
The production cycle took 7.5 months ± 1.5 SD on average. The mean stocking density was 5.5 ± 1.4 fingerlings per metre square. Fish yield per area per production cycle did not differ between the catfish and tilapia (t = 1.603, p = 0.120). The overall fish yield per hectare per production cycle was 1925 kg ± 915 SD. The selling price of the grown fish ranged from 1.7 to 3.8 USD per kilogramme (Fig. 2b). The selling price per kg of tilapia (mean = 3.5 USD ± 0.4 SD) was higher compared to the price of catfish (mean = 3.1 1 3 USD ± 0.5 SD) (t = 2.38, p = 0.024). Fish customers were highly available, and tilapia fish were preferred by the customers over catfish.
Sixty-six percent of the farmers used homemade feeds, while 34% used commercial feeds. Materials used for homemade feeds were maize bran, rice bran, sardines, blood meal, cassava meal, soybean meal, maggots, and kitchen leftovers. The majority of the farmers have not experienced disease outbreaks on their farms (Table 1). The types of diseases experienced by the farmers were fungal diseases (75%) and popeye (exophthalmia) disease (25%). The disease incidences were higher in catfish compared to tilapia fish (chi 2 = 5.052, d.f = 1, p = 0.024). In addition, nine farmers have experienced the mass death of fish due to poor water quality (n = 6), fungal diseases (n = 2), and poison (n = 1). The sources of water for the aquaculture were DUWASA, boreholes, and shallow dug wells (Table 1). Only 26% of the farmers added livestock manure to their ponds (Table 1). Availability and pricing of feeds and seeds were cited as the main challenges facing aquaculture development in the study area (Table 1). The average cost of commercial feed was USD 1.5 ± 0.2 SD per kilogramme.
The yield of the tilapia fish was associated with pond fertilisation, availability of extension services, source of feeds, type of ponds, source of water, stocking density, and pond age ( Table 2). The fish yield was higher where manure was used in the ponds, extension services were available, and commercial feeds were used (Fig. 3a, b and c). In addition, fish yield was lower in earthen ponds compared to concrete ponds, and in farmers who used water from shallow wells compared to boreholes (Fig. 3d and e). On the other hand, the fish yield had a unimodal relationship with stocking density, where it increased with stocking density to about 5 fish m −2 and declined afterwards (Fig. 4a). In addition, the yield has a linear relationship with pond age (Fig. 4b).
Catfish yield was also related to pond type, source of water, source of feeds, the availability of extension services, stocking density, and pond age ( Table 2). The yield was lower in earthen ponds than in concrete ponds, in farms that used water from shallow wells compared to boreholes, and higher when extension services were available and where commercial feeds were used. The fish yield increased with stocking density, reaching maximum yield at about 10 fish m − 2 (Fig. 5a). Furthermore, the yield increased with pond age (Fig. 5b).

Discussion
The study assessed the status, management practices, and challenges facing aquaculture development in the Dodoma region. The results show that fish farming in Dodoma began just 9 years ago, corresponding to the time when the region started to grow rapidly. Despite the fact that there are customers and fish are reasonably priced, the growth of aquaculture is minimal. The average fish yield was about 1925 kg ha −1 per culture cycle. High fish yield was associated with the use of commercial feeds, the use of manure in the ponds, access to extension services, and the age of the farm, whereas stocking density had a unimodal relationship with yield. Most of the key factors restricting aquaculture expansion in the region have been identified as the lack of water supply, poor extension services, and the cost and availability of fish feeds and seeds.
As with other parts of Tanzania, the Dodoma region has great potential for aquaculture development, which is not fully tapped. Fish farming is a small-scale activity where farmers own a few small ponds. The region has a growing population and limited sources of wild fish due to the aridity and its location away from the coast, providing opportunities for aquaculture expansion (Bwathondi and Mwamsojo 1993;Turner et al. 2019;Gayo 2021). Since most of the farms were new, proper training of the farmers on good management practises will improve fish production. The production cycle (7.5 months) was rather longer compared to other studies, e.g. 5.8 months (Chenyambuga et al. 2012), 6 months (Kohinoor et al. 1999), and 6.4 months (Chenyambuga et al. 2014). However, fish yield (kg ha −1 ) per culture cycle was relatively low compared to other parts of the country (Shoko Relationship between fish yield and a stocking density and b pond age in catfish production. The yield increased with stocking density, reaching a maximum yield at about 10 fish m −2 and also increased with pond age fish yields. Effective extension service is one of the main aspects required for aquaculture development (Mzula et al. 2021;Ragasa et al. 2022). Due to a low number of extension staff in this field, the extension services do not reach the majority of fish farmers (Mosha and Daudi 2020;Mzula et al. 2021). The University of Dodoma has established a bachelor's degree in aquaculture and aquatic sciences, which should offer immediate benefits to the fishing sector in the region. The growth of aquaculture in the region will create a winwin situation where students from the university will acquire a place for practical training and offer extension services to the farmers after completion of their studies. Feeds are an important input for sustainable aquaculture development in Tanzania. Commercial feeds are insufficient and have high prices that are unaffordable by many small-scale farmers (Rukanda and Sigurgeirsson 2018). As a result, many smallscale farmers focus on alternative sources of feed, especially agro-industrial by-products (Madalla 2008;Mmanda et al. 2020). Several studies have shown that the local ingredients of fish feeds contain a reasonable amount of nutrients (Madalla 2008;Munguti et al. 2012;Mmanda et al. 2020). Thus, there is a potential to improve profit by using farm-made feeds that are cheaper than commercial feeds. However, knowledge of the proper mixing of the feed ingredients to ensure a balance of essential amino acids and other nutrients is necessary (Rukanda and Sigurgeirsson 2018). In this study, both tilapia and catfish farmers who used commercial feeds reported a higher fish yield compared to those who used farm-made feeds (Table 2). This is due to improper mixing of the local feed ingredients and storage methods that reduce nutrients (Robb et al. 2013;Rukanda and Sigurgeirsson 2018). Furthermore, many farmers have limited knowledge of feed quality and fish nutritional requirements (Rukanda and Sigurgeirsson 2018). Essential nutrient deficiency reduces fish growth and health (Oliva-Teles 2012; Prabu et al. 2017). Similar studies have shown the good performance of fish fed commercial feeds compared to fish fed farm-made feeds (Opiyo et al. 2014;Olufeagba et al. 2016;Tadesse and Yimer 2021). However, when well-formulated, farm-made fish feeds boost aquaculture production by reducing the cost of production (Musiba et al. 2014;Opiyo et al. 2014).
The availability of fish feed is a challenge for most developing countries in Africa, Asia, and Latin America (Gabriel et al. 2007;Hasan et al. 2007;Kaleem and Sabi 2021). The majority of small and medium-scale farmers in these countries depend on farm-made feeds (Hasan et al. 2007;El-Sayed 2013;Hecht 2013). Earthen ponds are normally used, where organic manure is used to promote the production of natural fish food in the ponds (Hasan et al. 2007;Hecht 2013;Shoko et al. 2019). Integration of aquaculture with animal and crop production is normally done to ensure the availability of organic fertilisers (Prein 2002;Hasan et al. 2007;Shoko et al. 2019). Throughout Asia, the cultivation of rice is integrated with naturally occurring or introduced fish and other aquatic species (Prein 2002;Van Huong et al. 2018;Freed et al. 2020).
Vegetable production was the most common type of integration practised by the farmers in this study, and this finding agrees with Mulokozi et al. (2021). Apart from income generation through selling vegetables, vegetable waste is used for pond fertilisation Mulokozi et al. 2021). In this study, only one farmer integrated livestock with fish because livestock keeping requires a large investment in feed. As a result, most farmers could not get manure to apply to their ponds, as only 26% of the farmers added manure to their ponds. Livestock keepers in arid areas normally travel a long distance with their animals during the day to search for pasture and water. Manure is collected only at the night when the animals are confined in traditional enclosures. The benefits of adding manure to the ponds were evident in both tilapia and catfish production, as the farmers who added manure to their ponds reported higher fish yields compared to those who did not add manure to their ponds. Thus, farmers should be encouraged to keep animals like chickens to ensure a continuous supply of manure. Research by Zhu et al. (1990), Knud-Hansen et al. (1993), Green et al. (2002), and Shoko et al. (2019) reported similar findings on the contribution of manure to fish yield.
Sustainable aquaculture depends on the availability of good quality fingerlings (Kajungiro et al. 2019;Kaleem and Sabi 2021). However, the availability and quality of fingerlings are still poor in Tanzania due to low technology, limited knowledge, and a low level of investment (Rukanda and Sigurgeirsson 2018;Kajungiro et al. 2019). According to Kajungiro et al. (2019), there are only twelve producers of fish seeds in the whole country, and they are mainly located in Dar es Salaam and in the coastal region. As a result, small-scale farmers are forced to obtain seeds from each other or from the wild environment (van der Heijden et al. 2018;Kajungiro et al. 2019). The price of fingerlings is also high, especially catfish fingerlings. According to van der Heijden et al. (2018), approximately 70% of fish hatcheries in Tanzania produce tilapia fingerlings, while only 30% produce catfish fingerlings (van der Heijden et al. 2018). In addition, tilapia and catfish broodstock are imported from breeding stations in Uganda and Thailand, respectively (Rukanda and Sigurgeirsson 2018), increasing the prices of fingerlings. To reduce the import costs, wild parents of tilapia are obtained from Lake Victoria and catfish from rivers (Rukanda and Sigurgeirsson 2018;van der Heijden et al. 2018). According to van der Heijden et al. (2018), 60% of catfish seed producers in the country use wild broodstocks. The use of wild broodstocks and fingerlings hinders aquaculture development because of the mixing of species in the wild (Kajungiro et al. 2019). In Dodoma, people collect catfish fingerlings in drainage channels on the roadside and in ponds during the rainy season. The fingerlings are then sold to pond owners for a cheap price.
Water is an important resource in aquaculture development. Fish require high quality water with optimum levels of oxygen, pH, salinity, turbidity, and ammonia (Bhatnagar and Devi 2013;Devi et al. 2017). As a result, the pond water needs to be monitored for proper growth and the well-being of the fish. The sources of water for aquaculture in Tanzania are rivers, streams, and wetlands. However, perennial rivers and streams are limited in arid areas, so fish farming depends on tap water and private boreholes and shallow wells (Mapfumo 2011). In this study, 48% of farmers relied on tap water from DUWASA, while 35% relied on boreholes. However, the demand for water in Dodoma has increased rapidly due to population growth (Msongaleli et al. 2022), so the supply of tap water is low and unreliable. In addition, the tap water charges are high, increasing the production costs. Drilled boreholes ensure a continuous supply of water, but the construction costs are very high and unaffordable for small-scale farmers. Nevertheless, the tilapia and catfish farmers who used tap water and boreholes reported higher fish output than those who used water from shallow wells. The shallow wells are created using traditional and locally available tools, and their water yield depends on the amount of rainfall in a specific year (Hecht 2013). The wells normally dry up early in years with low rainfall (Shemsanga et al. 2018), challenging the fish farming.
Earthen ponds are the dominant type of pond used by small-scale farmers in Tanzania because they are cheaper to construct and promote the production of natural fish food through primary productivity (Rukanda and Sigurgeirsson 2018;Mmanda et al. 2020). However, earthen ponds are better suited to areas where water is readily available and soils have a high water-holding capacity (Yarhere 2009). To conserve water, the majority of farmers in our study had concrete and polythene-lined ponds. Furthermore, both tilapia and catfish farmers with concrete ponds reported higher fish yields than those with earthen ponds, possibly due to problems with water quality management in earthen ponds (Makori et al. 2017). However, earthen ponds have been shown to promote fish growth and yield (Adebayo and Adesoji 2008;Ester 2013;Ifedayo et al. 2020).
Stocking density is regarded as an important factor influencing fish growth, feed utilisation, and fish yield (Gibtan et al. 2008;Kapinga et al. 2014). In many cultivated fish species, growth is inversely related to stocking density (Gibtan et al. 2008;Kunda et al. 2021). The optimal stocking density for tilapia fish is thought to be between 3 and 5 fish m −2 (Alebachew et al. 2022). The tilapia yield in this study increased with stocking density to an intermediate density of about 5 fish m −2 , then started to decline. The decrease in yield at high densities can be explained by food competition and other density-dependent stressors at high stocking densities that lead to slower growth (Alebachew et al. 2022). A similar relationship was found by Gibtan et al. (2008). Alebachew et al. (2022) found that the mean final weight of tilapia increased with stocking density from 2 to 4 fish m −2 but decreased at 6 fish m −2 . The yield of catfish increased with stocking density, reaching a maximum yield at about 10 fish m −2 , indicating that they can tolerate higher stocking densities than tilapia. Aside from completion, high stocking density decreased water quality, but it is tolerable to catfish than tilapia (Akinwole and Faturoti 2007). A similar result was observed by Oké and Goosen (2019) who found that catfish yield increased significantly with density, reaching a maximum yield at a stocking density of 10 fish m −2 . Growth rate and weight gain peaked at a stocking density of 7 fish m −2 (Oké and Goosen 2019). Furthermore, the yield increased with pond age in both species. Pond age influences the availability of natural food through primary productivity and water quality (Hasibuan et al. 2021), increasing the growth of fish.
Fish diseases were not regarded as a challenge by farmers in this study because approximately 78% of the farmers had never encountered fish diseases, most likely due to the fact that the majority of the farms were established 3 years ago. Furthermore, the farmers did not use river or stream water, which has been linked to fish diseases and parasite infections (Mdegela et al. 2011;Chitmanat et al. 2016). Farmers who had experienced fish disease linked the problem to poor water quality. About 75% of the diseases reported by the farmers were fungal. Fish have fewer fungal diseases than other vertebrates, and the majority of the fungi that affect fish are opportunists. They attack the fish when they are stressed by unfavourable environmental conditions, bacterial and viral infections, poor nutrition, or physical trauma (Khoo 2000;Yanong 2003;Noga 2021). Popeye disease and other eye abnormalities are common symptoms of tilapia infection (Siti-Zahrah et al. 2008;Faruk et al. 2017).
The farmers reported more disease problems with catfish compared to tilapia. Fungal infections are common in catfish hatcheries, affecting both eggs and young fish (Walakira et al. 2014;Melaku et al. 2017). The fungal infections also affect adult and brood stocks of catfish (Melaku et al. 2017). It is important to educate farmers on good management practises that improve water quality and the body condition of the fish in order to reduce secondary fungal infections. Aquaponics and other integrated aquaculture practises are important for aquaculture development in arid regions with limited water supplies and in urban areas with limited space for extensive farming (Joyce et al. 2019).

Conclusion
Aquaculture production in Dodoma is a young endeavour that just began 9 years ago, necessitating the strengthening of extension services. Nile tilapia and African catfish are farmed in small ponds. The primary issues preventing the development of aquaculture in the region were determined to be the availability and cost of fish feed and seeds. Some 1 3 farmers were forced to use homemade feeds due to the high prices and scarcity of commercial feeds. Farmers who used commercial feeds, however, reported greater fish yields. The farming relies on tap water or water from private boreholes and shallow wells, so the availability of water presents another difficulty. The fish yield was correlated with the source of the water, and farmers who used boreholes and tap water reported larger fish yields than those who used shallow wells. Most farmers did not use manure in their ponds, but those who did had increased fish productivity. Extension services were generally accessible and were linked to increased fish yields. The study suggests improving extension services and educating farmers on modern farming techniques and best practices. This should cover water management, breeding, and feeding, among other things. To lower water demands, integrated aquaculture should be encouraged, including water recycling and aquaponics.