An Ecological and Economical Assessment of Integrated Amaranth (Amaranthus hybridus) and Nile Tilapia (Oreochromis niloticus) Farming in Dar es Salaam, Tanzania

Abstract

Organic wastes can be recycled in an ecologically sound way in fishponds by applying integrated agriculture and aquaculture systems (IAA). This kind of waste recycling can help to protect the environment from pollution and improve fishpond yields. Additionally, IAA provides an opportunity for diversification of the output from two or more existing subsystems leading to higher overall farm economic returns. This study explored the potential application of amaranth wastes (AW) as a dietary ingredient for tilapia in a tilapia-amaranths integrated system (ITA). An experimental diet (AD) contained 10% (based on the control diet, CD) inclusion of AW collected from a nearby vegetable market. The experiments included triplicate treatments with; (i) fish fed on AD, where the pond water was used for irrigating the amaranth plants (IAA-fish), and (ii) fish fed on CD, where no pond water was used for irrigating the amaranth plants (non-IAA fish). 90 days after fish stocking, eighteen 4 m2 amaranth plots were prepared and treated with (i) tap water without fertilization (control amaranths), (ii) water from IAA-fish pond and organically fertilized (IAA amaranths), and (iii) tap water and inorganically fertilized (non-IAA amaranths). The use of AW improved the fish feed conversion ratio. The overall net income from ITA was 3.2, 2.3, 2.6, and 1.8 higher than from non-IAA amaranths, IAA-amaranths, non-IAA fish, and IAA fish sub-systems respectively.

Integration of Nile tilapia (Oreochromis niloticus) and vegetables (Amaranthus hybridus and Brassica rapa pekinensis) for improved production, water use efficiency and nutrient recycling

“…This is because the fish cultured in LSD had a more rapid growth and higher survival rate (100%) compared to the 83% found in MSD. The average fish yield (11 to 14 tons per ha) recorded in this study was similar to those reported previously (Mulokozi, Berg et al., 2020; Shoko et al., 2016; Toma et al., 2015), but higher than those (2–6 tons per ha) reported by other research in Tanzania (Chenyambuga et al., 2014; Limbu et al., 2017; Shoko et al., 2011). The reason for this is probably due to the fact that the present study involved the use of sex reversed tilapia cultured at high stocking densities compared to the use of mixed tilapia at lower stocking densities employed in previous studies in Tanzania.…”

“…These results are similar to those by Mulokozi, Berg, et al. (2020), who reported a significantly higher yield for the first amaranth harvest, which was irrigated with fish pond water in an IAA system, than the amaranth yield in a non‐IAA system irrigated with tap water. Considering the high fish mortality recorded in HSD and the fact that both Mo and Ho gave the same yield as NO, while Lo were lower, this indicates that an IAA system can benefit from slightly higher stocking density than five fish m −3 , but if it becomes too high, the fish could easily die due to a decreased water quality.…”

“…For example, Mulokozi, Berg, et al. (2020) in Dar es Salaam reported that the net income from the integration of fish and amaranth was 3.2, 2.3, 2.6, and 1.8 higher than from non‐IAA amaranths, IAA‐amaranths, non‐IAA fish, and IAA fish subsystems, respectively. In an experiment involving fish‐vegetable integrated system in Kilombero, Limbu et al.…”

Feminist discourses on utu and heshima in selected works by Tanzanian women writers

“…I would extend the reference, namely, "classical poetry", to even modern compositions that follow the 18th-century models of prosody, scansion and rhyming. I should note too that I document the lexis found in modern compositions that do not fit within the classical model, e.g., the poetry of Kezilahabi plus others cited in the project's Bibliography, Kahigi and Mulokozi (1976), Mulokozi and Kahigi (1979). Poets are wordsmiths; and the modern poets are on the cutting edge of the lexical growth of a language, as were the classical poets in their own time.…”

Capturing the lexical richness of Swahili poetry

“…I would extend the reference, namely, "classical poetry", to even modern compositions that follow the 18th-century models of prosody, scansion and rhyming. I should note too that I document the lexis found in modern compositions that do not fit within the classical model, e.g., the poetry of Kezilahabi plus others cited in the project's Bibliography, Kahigi and Mulokozi (1976), Mulokozi and Kahigi (1979). Poets are wordsmiths; and the modern poets are on the cutting edge of the lexical growth of a language, as were the classical poets in their own time.…”