Spirulina (Arthrospira fusiformis) as a potential protein source in practical diets for fry mariculture of Rufiji tilapia (Oreochromis urolepis urolepis)

Deogratias P Mulokozi,Aviti J Mmochi,Matern S Mtolera

doi:10.4314/wiojms.v18i2.6

Abstract

The effects on growth performance, feed utilization, survival and whole fish body proximate composition of replacing fishmeal (Rastrineobola argentea) with a locally available spirulina species (Arthrospira fusiformis) as a protein ingredient in the feed of Rufiji tilapia (Oreochromis urolepis urolepis) fry was examined. Fishmeal replacement with A. fusiformis was carried out at 5%, 15%, 25%, 35% and 100% (S5, S15, S25, S35 and S100), and the effect of the replacement was compared with the control diet (S0, 0% spirulina). Fish fry were stocked at an average initial weight of 0.57 g at 10 fish per 0.1 m3 and cultured for 60 days using full strength salt water (30-35 ppt). A. fusiformis was isolated from Momela Lake in Arusha National Park, Tanzania and propagated using selected culture media. It was observed that fish fry fed spirulina at a 5% fishmeal substitution level diet had better (p<0.05) final weight (8.48), average daily weight gain (0.132), specific growth rate (4.47), feed conversion rate (2.08) and protein efficiency ratio (1.37) compared to the control fish group. Growth performance in fish fed diet S15 was comparable with the control group (p>0.05). Spirulina supplementation had no effect on fish survival rates and meat quality. It appears that the Momella Lake spirulina may be an appropriate growth-stimulating plant protein when used as a feed additive in Rufiji tilapia mariculture.

Highlights

Aquaculture is currently the most rapidly growing food production sector, with an annual growth rate of more than 5.8% (FAO, 2018)
The results show considerable variation in the degree of success for partial and complete replacement depending on the spirulina strains, farmed fish species as well as the growth stage of fish
The present study evaluated the potential use of a locally sourced spirulina, A. fusiformis, as a protein source in practical diets for Rufiji tilapia mariculture

Summary

Introduction

Aquaculture is currently the most rapidly growing food production sector, with an annual growth rate of more than 5.8% (FAO, 2018). In line with global aquaculture growth, there is an increased demand for nutritionally sufficient and economically affordable aqua feeds (Thilsted et al, 2016). Fishmeal is the most preferred feed supplement in intensive and semi-intensive aquaculture systems (El-Saidy and Gaber, 2004). This is partly because it is considered most palatable and rich in essential amino acids, fatty acids, energy and minerals (Tacon, 1993; Hardy, 2010). Because global fisheries have leveled off at a time when there is increasing demand to feed the growing human population and to supply a fast-expanding fish meal industry, the availability of fish meal is limited (FAO, 2016). From an environmental perspective, overfishing the wild fishery for fishmeal production is unjustifiable (Wijkström, 2009)

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Conclusion