Evaluation Of The Effect Of The Partial Replacement Of Caridina Nilotica (P. Roux, 1833) With Spirulina, Arthrospira Platensis, (Gomont, 1892) On Water Quality Parameters And Growth Performance Of Cultured Nile Tilapia, Oreochromis Niloticus (Linnaeus, 1758).

Abstract

Tilapia is considered the best species for aquaculture production in Kenya and the world because it grows faster, has high tolerance to different environmental conditions and is easy to breed. However, tilapia culture faces the challenge of poor quality seeds, substandard and expensive feeds. Therefore, the present study was conducted in the University of Nairobi’s Aquaculture laboratory, Department of Biological Sciences to determine the outcome of replacing shrimps (Caridina nilotica) (P. Roux, 1833) with Spirulina (Arthrospira platensis) (Gomont, 1892) (Spirulina) on the growth performance of Oreochromis niloticus (Linnaeus, 1758) fry and on the water quality parameters. The study used five diets T0 - T4. Four of these treatment (T1 – T4) contained Arthrospira platensis (Gomont, 1892) as the protein source at the following levels respectively, 10, 20, 50 and 100% while the fifth one (T0) was the control diet with Caridina nilotica as the source of protein. The five treatment diets were tested in triplicate form in glass aquaria stocked with 300 fry with mean average weight of 1.6g. The Proximate Analysis of ingredients and formulated diets was examined using Association of Official Analytical Chemists (AOAC) methods. The effect of the different diets on growth parameters and water quality parameters were analysed using the analysis of variance (one-way ANOVA). Turkey’s multiple range tests was used to compare statistical difference among treatment means. Differences between the treatment means were considered significant at p < 0.05. There was no significant difference (p > 0.05) in the water quality parameters among the treatments. The nutritional composition of formulated diets was 35% crude protein, 4 to 6% moisture, 6 to 8% fibre, 37 to 41% carbohydrate and 322 to 323Kcal per 100g energy. Overall fish body weight increased significantly (p< 0.05) from 1.6g to 12g at the end of the experiment. Fish fed on T2 (20% Arthrospira platensis) had the highest weight gain (12.3g, p < 0.05) while fish fed T0 (control diet)) had the lowest weight gain (9.1g). No significant difference (p > 0.05) in weight gain was observed among fish fed T1 (10% A. platensis), T3 xii (50% A. platensis) and T4 (100% A. platensis). The specific growth rate was highest with T2 (3.6%) and lowest with T0 (3.3%). The mortality was 0% for all the different diets. The condition factor of the fish ranged from 1.2 to 1.8 (p<0.05) while the Feed Conversion Ratio FCR was in the range of 1.03-1.11 (p<0.05) with the highest being T2 and the lowest in T0. It can be concluded that, inclusion of A. platensis up to 20% in the diet of O. niloticus improves its growth performance and has no negative impact on the water quality and fish survival. However, the minimal advantage conferred by using A. Platensis may require a critical evaluation of its use against cost of aquaculture production.