Length-weight Relationship and Condition Factor of Juvenile Nile Tilapia Oreochromis niloticus (Linnaeus 1758) Fed Diets with Pyropia spheroplasts in Closed Recirculating System

Abstract

This study was conducted to assess the nutritional effects of Pyropia spheroplasts (PS) on the physical growth proportions of length-weight (L-W) relationship and condition factor (K) of juvenile Nile tilapia Oreochromis niloticus (Linnaeus 1758) in a closed recirculating system. Four different iso-energetic diets were prepared with different levels of PS (Diets 1 to 3) including a diet without PS as a control (Diet 4). Fish were fed with 38% protein diets and the results of this study showed that there was no significant difference (P>0.05) between groups according to protein intake. Experimental PS diets exhibited isometric (b=3) exponential growth, while control showed an allometric growth pattern (b<3). The coefficient of determination (r 2) of regression analysis was similar with all the dietary groups. The condition factor (K) varied from 1.2-1.7, while the highest value was observed in fish fed with Diet 3 (50 g. kg-1 PS) and the lowest was obtained in the control. Both regression coefficient (b) and condition factor indicated a proportional uniform growth pattern obtained in all PS levels. No negative effect was noted in the growth performance (P>0.05). Results showed that the PS can be used as fish feed ingredient for the proportional isometric growth of Nile tilapia.