Effect of simultaneous variation of weight, density, temperature and O2 concentration on rainbow trout (Oncorhynchus mykiss) body composition.

The simultaneous effect of weight, initial density (kg/m3, temperature and O2 concentration on rainbow trout body composition (fat, protein, moisture and ash) has been studied. In 3 successive experimental phases fish were kept in different lots of varying initial weight (178-372 g), initial density (7.2-38.8 kg/m3) and temperature (15-20 degrees C). Simple correlations were statistically significant for weight vs fat (r = 0.56; P less than 0.001) and moisture (r = -0.57; P less than 0.001); temperature vs fat (r = 0.73; P less than 0.001) moisture (r = -0.73; P less than 0.001) and ash (r = -0.26; P less than 0.02); and O2 concentration vs fat (r = 0.22; P less than 0.05). Multivariant equations for the different compounds were obtained. Only fat and moisture percentages showed significant differences (rm = 0.75; P less than 0.00005); an inverse relation existing between them (r = -0.94; P less than 0.001). Temperature is the factor which has the strongest influence on fat and moisture when it varies simultaneously with weight, initial density and O2 concentration, which is shown by its equation coefficients (P less than 0.00005).