The relationship between ammonia production and oxygen concentration in water and the biomass of eels and level of protein in the diet of Anguilla anguilla L.

Abstract

This study examined the influence of weight and protein level in their diet, on water quality (ammonia and oxygen concentrations, nitrate level, and pH) in the containers in which the eels were kept. A linear correlation was found between the time the eels were in the water, and ammonia production by them grouped by weight. The equation is A = 0·0782 W − 0·0456 where A = ammonia concentration (in ppm) per hour, and W = the weight (g) of eels. One kg of eels produced 24·99 mg ammonia per hour. The correlation between ammonia concentration, pH and nitrate did not change during the period of measurement in the present study. Ammonia concentration increased with an increase in the protein level in the diet. The equation is A = 0·01 D − 0·05 where A = ammonia concentration in water and D = % protein in the diet. The oxygen concentration in the water was inversely correlated with the weight of the eels, and the allometric equation for the relationship between body weight of fish and oxygen concentration (0 ppm) is 0 = −0·1925 W + 7·7760. The allometric equation for the relationship between oxygen concentration (0, ppm) and percent protein in the diet (D) is 0 = 0·016 D + 6·8790.