author(s)
Bhuneshwari Usandi, VP Saini, ML Ojha and HK Jain

abstract
The present study was conducted to optimize the larval rearing density for a freshwater ornamental fish ‘koi carp’. For this purpose, five different rearing densities i.e., 2500 (T₁), 5000 (T₂), 7500 (T₃), 10000 (T₄) & 12500/m³ (T₅) were tested using static water holdings (aquarium tank of 2'x1'x1' size). Koi larvae having an initial mean length and weight of 6±1 mm and 1±0.1mg respectively were stocked at five different rearing densities in triplicate. They were fed with live food (mixed zooplankton) and dry larval feed (crude protein 22%, crude fat 3%, fibre 8% and moisture 11%). The average maximum values in terms of net weight (0.0644g), length (22.7 mm) and specific growth rate (13.44) were observed in T₁. The highest survival was recorded in T₁ (62.67%) and lowest in T₅ (21.67%). The results revealed that stocking density had an inverse relationship with growth performance (length gain, weight gain, and specific growth rate) and survival. A rearing density of 7000m³ was calculated using the second order polynomial regression analysis between stocking density and total numbers of fry harvested.